The MySQL (TM) software delivers a very fast, multi-threaded,
multi-user, and robust SQL (Structured Query Language)
database server.
MySQL Server is intended for mission-critical, heavy-load
production systems as well as for embedding into mass-deployed software.
MySQL is a trademark of MySQL AB.
The MySQL software is Dual Licensed. Users can choose to
use the MySQL software as an Open Source/Free Software
product under the terms of the GNU General Public License
(http://www.gnu.org/licenses/) or can purchase a standard
commercial license from MySQL AB.
See section 1.4 MySQL Support and Licensing.
The MySQL web site (http://www.mysql.com/) provides the
latest information about the MySQL software.
The following list describes some sections of particular interest in this manual:
MySQL Database Server,
see section 1.3 What Is MySQL AB?.
MySQL Database Server,
see section 1.2.2 The Main Features of MySQL.
MySQL Database Software to new architectures
or operating systems, see section E Porting to Other Systems.
MySQL Database Server,
see section 3 Tutorial Introduction.
SQL and benchmarking information, see the
benchmarking directory (`sql-bench' in the distribution).
Important:
Reports of errors (often called bugs), as well as questions and comments, should be sent to the mailing list at mysql@lists.mysql.com. See section 1.6.1.3 How to Report Bugs or Problems.
The mysqlbug script should be used to generate bug reports.
For source distributions, the mysqlbug script can be found in the
`scripts' directory. For binary distributions, mysqlbug
can be found in the `bin' directory (`/usr/bin' for the
MySQL-server RPM package).
If you have found a sensitive security bug in MySQL Server,
you should send an e-mail to security@mysql.com.
This is the MySQL reference manual; it documents MySQL
up to Version 3.23.56. Functional changes are always
indicated with reference to the version, so this manual is also suitable
if you are using an older version of the MySQL software.
Being a reference manual, it does not provide general instruction on
SQL or relational database concepts.
As the MySQL Database Software is under constant development,
the manual is also updated frequently.
The most recent version of this manual is available at
http://www.mysql.com/documentation/ in many different formats,
including HTML, PDF, and Windows HLP versions.
The primary document is the Texinfo file.
The HTML version is produced automatically using a modified version of
texi2html.
The plain text and Info versions are produced with makeinfo.
The PostScript version is produced using texi2dvi and dvips.
The PDF version is produced with pdftex.
If you have a hard time finding information in the manual, you can try our searchable version at http://www.mysql.com/doc/.
If you have any suggestions concerning additions or corrections to this manual, please send them to the documentation team at docs@mysql.com.
This manual was initially written by David Axmark and Michael (Monty) Widenius. It is currently maintained by Michael (Monty) Widenius, Arjen Lentz, and Paul DuBois. For other contributors, see section C Credits.
The copyright (2003) to this manual is owned by the Swedish company
MySQL AB. See section 1.4.2 Copyrights and Licenses Used by MySQL.
This manual uses certain typographical conventions:
constant
mysqladmin works, invoke it with the
--help option.''
When commands are shown that are meant to be executed by a particular
program, the program is indicated by a prompt shown before the command. For
example, shell> indicates a command that you execute from your login
shell, and mysql> indicates a command that you execute from the
mysql client program:
shell> type a shell command here mysql> type a mysql command here
Shell commands are shown using Bourne shell syntax. If you are using a
csh-style shell, you may need to issue commands slightly differently.
For example, the sequence to set an environment variable and run a command
looks like this in Bourne shell syntax:
shell> VARNAME=value some_command
For csh, you would execute the sequence like this:
shell> setenv VARNAME value shell> some_command
Often database, table, and column names must be substituted into commands. To
indicate that such substitution is necessary, this manual uses
db_name, tbl_name and col_name. For example, you might
see a statement like this:
mysql> SELECT col_name FROM db_name.tbl_name;
This means that if you were to enter a similar statement, you would supply your own database, table, and column names, perhaps like this:
mysql> SELECT author_name FROM biblio_db.author_list;
SQL keywords are not case-sensitive and may be written in uppercase or lowercase. This manual uses uppercase.
In syntax descriptions, square brackets (`[' and `]') are used
to indicate optional words or clauses. For example, in the following
statement, IF EXISTS is optional:
DROP TABLE [IF EXISTS] tbl_name
When a syntax element consists of a number of alternatives, the alternatives are separated by vertical bars (`|'). When one member from a set of choices may be chosen, the alternatives are listed within square brackets (`[' and `]'):
TRIM([[BOTH | LEADING | TRAILING] [remstr] FROM] str)
When one member from a set of choices must be chosen, the alternatives are listed within braces (`{' and `}'):
{DESCRIBE | DESC} tbl_name {col_name | wild}
MySQL, the most popular Open Source SQL database, is
developed, distributed and supported by MySQL AB. MySQL AB is a
commercial company founded by the MySQL developers that builds its business
providing services around the MySQL database.
See section 1.3 What Is MySQL AB?.
The MySQL web site (http://www.mysql.com/)
provides the latest information about MySQL software and
MySQL AB.
MySQL is a database management system.
MySQL Server. Since computers are very good at handling large
amounts of data, database management plays a central role in computing,
as stand-alone utilities, or as parts of other applications.
SQL part of
``MySQL'' stands for ``Structured Query Language''@-the
most common standardised language used to access databases.
Open Source.
Open Source means that it is possible for anyone to use and modify.
Anybody can download the MySQL software from the Internet and use it
without paying anything. Anybody so inclined can study the source code
and change it to fit their needs. The MySQL software uses the
GPL (GNU General Public License),
http://www.gnu.org/licenses/, to define what you
may and may not do with the software in different situations.
If you feel uncomfortable with the GPL or need to embed
MySQL code into a commercial application you can buy a
commercially licensed version from us.
See section 1.4.3 MySQL Licenses.
MySQL Database Server is very fast, reliable, and easy to use.
If that is what you are looking for, you should give it a try.
MySQL Server also has a practical set of features developed in
close cooperation with our users. You can find a performance comparison
of MySQL Server to some other database managers on our benchmark page.
See section 5.1.4 The MySQL Benchmark Suite.
MySQL Server was originally developed to handle large databases
much faster than existing solutions and has been successfully used in
highly demanding production environments for several years. Though
under constant development, MySQL Server today offers a rich and
useful set of functions. Its connectivity, speed, and security make
MySQL Server highly suited for accessing databases on the Internet.
MySQL Database Software is a client/server system that consists
of a multi-threaded SQL server that supports different backends,
several different client programs and libraries, administrative tools,
and a wide range of programming interfaces (APIs).
We also provide MySQL Server as a multi-threaded library which you
can link into your application to get a smaller, faster, easier-to-manage
product.
MySQL Database Server.
The official way to pronounce MySQL is ``My Ess Que Ell'' (not
``my sequel''), but we don't mind if you pronounce it as ``my sequel''
or in some other localised way.
We once started out with the intention of using mSQL to connect to our
tables using our own fast low-level (ISAM) routines. However, after some
testing we came to the conclusion that mSQL was not fast enough nor
flexible enough for our needs. This resulted in a new SQL interface to our
database but with almost the same API interface as mSQL. This API was
chosen to ease porting of third-party code.
The derivation of the name MySQL is not perfectly clear. Our base
directory and a large number of our libraries and tools have had the prefix
``my'' for well over 10 years. However, Monty's daughter (some years younger)
is also named My. Which of the two gave its name to MySQL is
still a mystery, even for us.
The following list describes some of the important characteristics
of the MySQL Database Software. See section 1.5 MySQL 4.x In A Nutshell.
MySQL code gets tested with Purify
(a commercial memory leakage detector) as well as with Valgrind,
a GPL tool (http://developer.kde.org/~sewardj/).
FLOAT, DOUBLE, CHAR, VARCHAR,
TEXT, BLOB, DATE, TIME, DATETIME,
TIMESTAMP, YEAR, SET, and ENUM types.
See section 6.2 Column Types.
INSERT to insert a subset of a table's columns; those
columns that are not explicitly given values are set to their default
values.
SELECT and WHERE
parts of queries. For example:
mysql> SELECT CONCAT(first_name, " ", last_name)
-> FROM tbl_name
-> WHERE income/dependents > 10000 AND age > 30;
GROUP BY and ORDER BY clauses with
expressions. Support for group functions (COUNT(),
COUNT(DISTINCT ...), AVG(), STD(), SUM(),
MAX(), and MIN()).
LEFT OUTER JOIN and RIGHT OUTER JOIN with ANSI
SQL and ODBC syntax.
DELETE, INSERT, REPLACE, and UPDATE return
the number of rows that were changed (affected). It is possible to return
the number of rows matched instead by setting a flag when connecting to the
server.
MySQL-specific SHOW command can be used to retrieve
information about databases, tables, and indexes. The EXPLAIN command
can be used to determine how the optimiser resolves a query.
ABS is a valid column name. The only restriction is that for a
function call, no spaces are allowed between the function name and the
`(' that follows it. See section 6.1.7 Is MySQL Picky About Reserved Words?.
MySQL Server with some
databases that contain 50 million records and we know of users that
use MySQL Server with 60,000 tables and about 5,000,000,000 rows.
MySQL Server).
An index may use a prefix of a CHAR or VARCHAR field.
MySQL server using TCP/IP Sockets,
Unix Sockets (Unix), or Named Pipes (NT).
ODBC (Open-DataBase-Connectivity) support for Win32 (with source).
All ODBC 2.5 functions and many others. For example, you can use
MS Access to connect to your MySQL server. See section 8.3 MySQL ODBC Support.
MySQL
server is started. To see an example of very advanced sorting, look
at the Czech sorting code. MySQL Server supports many different
character sets that can be specified at compile and runtime.
myisamchk, a very fast utility for table checking,
optimisation, and repair. All of the functionality of myisamchk
is also available through the SQL interface as well.
See section 4 Database Administration.
MySQL programs can be invoked with the --help or -?
options to obtain online assistance.
This section addresses the questions ``How stable is MySQL Server?'' and ``Can I depend on MySQL Server in this project?'' We will try to clarify these issues and answer some important questions that concern many potential users. The information in this section is based on data gathered from the mailing list, which is very active in identifying problems as well as reporting types of use.
Original code stems back from the early '80s, providing a stable code
base, and the ISAM table format remains backward-compatible.
At TcX, the predecessor of MySQL AB, MySQL code has worked
in projects since mid-1996, without any problems.
When the MySQL Database Software was released to a wider public,
we noticed that there were
some pieces of ``untested code'' that were quickly found by the new
users who made different types of queries from us. Each new release
has had fewer portability problems (even though each new release has
had many new features).
Each release of the MySQL Server has been usable. There have only
been problems
when users try code from the ``gray zones.'' Naturally, new users
don't know what the gray zones are; this section attempts to indicate
those that are currently known.
The descriptions mostly deal with Version 3.23 of MySQL Server.
All known and reported bugs are fixed in the latest version, with the
exception of those listed in the bugs section, which are things that
are design-related. See section 1.7.5 Known Errors and Design Deficiencies in MySQL.
The MySQL Server design is multi-layered with independent modules.
Some of the newer modules are listed here with an indication of how
well-tested each of them is:
MySQL 4.x.
InnoDB tables -- Stable (in 3.23 from 3.23.49)
InnoDB transactional storage engine has now been declared
stable in the MySQL 3.23 tree, starting from version 3.23.49.
InnoDB is being used in large, heavy-load production systems.
BDB tables -- Gamma
Berkeley DB code is very stable, but we are still improving
the BDB transactional storage engine interface in
MySQL Server, so it will take some time before this is as well
tested as the other table types.
FULLTEXT -- Beta
MySQL 4.0.
MyODBC 2.50 (uses ODBC SDK 2.5) -- Gamma
MyISAM tables -- Gamma
MyISAM storage
engine that checks if the table was closed properly on open and
executes an automatic check/repair of the table if it wasn't.
MyISAM tables in MySQL 4.0 for faster
insert of many rows.
fcntl()). In these cases, you should
run mysqld with the --skip-external-locking flag.
Problems are known to occur on some Linux systems, and on SunOS when
using NFS-mounted filesystems.
MySQL AB provides high-quality support for paying customers,
but the MySQL mailing list usually provides answers to common
questions. Bugs are usually fixed right away with a patch; for serious
bugs, there is almost always a new release.
MySQL Version 3.22 has a 4G limit on table size. With the new
MyISAM table type in MySQL Version 3.23, the maximum table
size is pushed up to 8 million terabytes (2 ^ 63 bytes).
Note, however, that operating systems have their own file-size limits. Here are some examples:
| Operating System | File-Size Limit |
| Linux-Intel 32 bit | 2G, 4G or more, depends on Linux version |
| Linux-Alpha | 8T (?) |
| Solaris 2.5.1 | 2G (possible 4G with patch) |
| Solaris 2.6 | 4G (can be changed with flag) |
| Solaris 2.7 Intel | 4G |
| Solaris 2.7 UltraSPARC | 512G |
On Linux 2.2 you can get bigger tables than 2G by using the LFS patch for the ext2 filesystem. On Linux 2.4 patches also exist for ReiserFS to get support for big files.
This means that the table size for MySQL databases is normally
limited by the operating system.
By default, MySQL tables have a maximum size of about 4G. You can
check the maximum table size for a table with the SHOW TABLE STATUS
command or with the myisamchk -dv table_name.
See section 4.5.6 SHOW Syntax.
If you need bigger tables than 4G (and your operating system supports
this), you should set the AVG_ROW_LENGTH and MAX_ROWS
parameter when you create your table. See section 6.5.3 CREATE TABLE Syntax. You can
also set these later with ALTER TABLE. See section 6.5.4 ALTER TABLE Syntax.
If your big table is going to be read-only, you could use
myisampack to merge and compress many tables to one.
myisampack usually compresses a table by at least 50%, so you can
have, in effect, much bigger tables. See section 4.7.4 myisampack, The MySQL Compressed Read-only Table Generator.
You can go around the operating system file limit for MyISAM data
files by using the RAID option. See section 6.5.3 CREATE TABLE Syntax.
Another solution can be the included MERGE library, which allows
you to handle a collection of identical tables as one.
See section 7.2 MERGE Tables.
The MySQL Server itself has no problems with Year 2000 (Y2K)
compliance:
MySQL Server uses Unix time functions and has no problems with dates
until 2069; all 2-digit years are regarded to be in the range
1970 to 2069, which means that if you store 01 in a
year column, MySQL Server treats it as 2001.
MySQL date functions are stored in one file, `sql/time.cc',
and are coded very carefully to be year 2000-safe.
MySQL Version 3.22 and later, the new YEAR column type
can store years 0 and 1901 to 2155 in 1 byte and
display them using 2 or 4 digits.
You may run into problems with applications that use MySQL Server
in a way that is not Y2K-safe. For example, many old applications store
or manipulate years using 2-digit values (which are ambiguous) rather than
4-digit values. This problem may be compounded by applications that use
values such as 00 or 99 as ``missing'' value indicators.
Unfortunately, these problems may be difficult to fix because different applications may be written by different programmers, each of whom may use a different set of conventions and date-handling functions.
Here is a simple demonstration illustrating that MySQL Server
doesn't have any problems with dates until the year 2030:
mysql> DROP TABLE IF EXISTS y2k;
Query OK, 0 rows affected (0.01 sec)
mysql> CREATE TABLE y2k (date DATE,
-> date_time DATETIME,
-> time_stamp TIMESTAMP);
Query OK, 0 rows affected (0.00 sec)
mysql> INSERT INTO y2k VALUES
-> ("1998-12-31","1998-12-31 23:59:59",19981231235959),
-> ("1999-01-01","1999-01-01 00:00:00",19990101000000),
-> ("1999-09-09","1999-09-09 23:59:59",19990909235959),
-> ("2000-01-01","2000-01-01 00:00:00",20000101000000),
-> ("2000-02-28","2000-02-28 00:00:00",20000228000000),
-> ("2000-02-29","2000-02-29 00:00:00",20000229000000),
-> ("2000-03-01","2000-03-01 00:00:00",20000301000000),
-> ("2000-12-31","2000-12-31 23:59:59",20001231235959),
-> ("2001-01-01","2001-01-01 00:00:00",20010101000000),
-> ("2004-12-31","2004-12-31 23:59:59",20041231235959),
-> ("2005-01-01","2005-01-01 00:00:00",20050101000000),
-> ("2030-01-01","2030-01-01 00:00:00",20300101000000),
-> ("2050-01-01","2050-01-01 00:00:00",20500101000000);
Query OK, 13 rows affected (0.01 sec)
Records: 13 Duplicates: 0 Warnings: 0
mysql> SELECT * FROM y2k;
+------------+---------------------+----------------+
| date | date_time | time_stamp |
+------------+---------------------+----------------+
| 1998-12-31 | 1998-12-31 23:59:59 | 19981231235959 |
| 1999-01-01 | 1999-01-01 00:00:00 | 19990101000000 |
| 1999-09-09 | 1999-09-09 23:59:59 | 19990909235959 |
| 2000-01-01 | 2000-01-01 00:00:00 | 20000101000000 |
| 2000-02-28 | 2000-02-28 00:00:00 | 20000228000000 |
| 2000-02-29 | 2000-02-29 00:00:00 | 20000229000000 |
| 2000-03-01 | 2000-03-01 00:00:00 | 20000301000000 |
| 2000-12-31 | 2000-12-31 23:59:59 | 20001231235959 |
| 2001-01-01 | 2001-01-01 00:00:00 | 20010101000000 |
| 2004-12-31 | 2004-12-31 23:59:59 | 20041231235959 |
| 2005-01-01 | 2005-01-01 00:00:00 | 20050101000000 |
| 2030-01-01 | 2030-01-01 00:00:00 | 20300101000000 |
| 2050-01-01 | 2050-01-01 00:00:00 | 00000000000000 |
+------------+---------------------+----------------+
13 rows in set (0.00 sec)
This shows that the DATE and DATETIME types will not
give any problems with future dates (they handle dates until the year
9999).
The TIMESTAMP type, which is used to store the current time, has a
range up to only 2030-01-01. TIMESTAMP has a range of
1970 to 2030 on 32-bit machines (signed value). On 64-bit
machines it handles times up to 2106 (unsigned value).
Even though MySQL Server is Y2K-compliant, it is your responsibility
to provide unambiguous input. See section 6.2.2.1 Y2K Issues and Date Types for MySQL Server's
rules for dealing with ambiguous date input data (data containing 2-digit
year values).
MySQL AB is the company of the MySQL founders and main
developers. MySQL AB was originally established in Sweden by
David Axmark, Allan Larsson, and Michael Monty Widenius.
All the developers of the MySQL server are employed by the company.
We are a virtual organisation with people in a dozen countries around
the world. We communicate extensively over the Net every day with each
other and with our users, supporters and partners.
We are dedicated to developing the MySQL software and spreading
our database to new users. MySQL AB owns the copyright to the
MySQL source code, the MySQL logo and trademark, and this
manual. See section 1.2 What Is MySQL?.
The MySQL core values show our dedication to MySQL and
Open Source.
We want the MySQL Database Software to be:
MySQL AB and the people at MySQL AB:
Open Source philosophy and support the
Open Source community.
The MySQL web site (http://www.mysql.com/)
provides the latest information about MySQL and MySQL AB.
One of the most common questions we encounter is: ``How can you make a living from something you give away for free?'' This is how.
MySQL AB makes money on support, services, commercial licenses,
and royalties, and we use these revenues to fund product development
and to expand the MySQL business.
The company has been profitable since its inception. In October 2001, we accepted venture financing from leading Scandinavian investors and a handful of business angels. This investment is used to solidify our business model and build a basis for sustainable growth.
MySQL AB is run and owned by the founders and main developers of
the MySQL database. The developers are committed to giving support
to customers and other users in order to stay in touch with their needs
and problems. All our support is given by qualified developers. Really
tricky questions are answered by Michael Monty Widenius, principal
author of the MySQL Server.
See section 1.4.1 Support Offered by MySQL AB.
For more information and ordering support at various levels, see http://www.mysql.com/support/ or contact our sales staff at sales@mysql.com.
MySQL AB delivers MySQL and related training worldwide.
We offer both open courses and in-house courses tailored to the
specific needs of your company. MySQL Training is also available
through our partners, the Authorised MySQL Training Centers.
Our training material uses the same example databases as our
documentation and our sample applications, and it is always updated
to reflect the latest MySQL version. Our trainers are backed by
the development team to guarantee the quality of the training and the
continuous development of the course material. This also ensures
that no questions raised during the courses remain unanswered.
Attending our training courses will enable you to achieve your goals
related to your MySQL applications. You will also:
MySQL Certification.
If you are interested in our training as a potential participant or as a training partner, please visit the training section at http://www.mysql.com/training/ or contact us at: training@mysql.com.
For details about the MySQL Certification Program, please see
http://www.mysql.com/certification/.
MySQL AB and its Authorised Partners offer consulting
services to users of MySQL Server and to those who embed
MySQL Server in their own software, all over the world.
Our consultants can help you design and tune your databases, construct
efficient queries, tune your platform for optimal performance, resolve
migration issues, set up replication, build robust transactional
applications, and more.
We also help customers embed MySQL Server in their products and
applications for large-scale deployment.
Our consultants work in close collaboration with our development team,
which ensures the technical quality of our professional services.
Consulting assignments range from 2-day power-start sessions to
projects that span weeks and months. Our expertise not only covers
MySQL Server, but also extends into programming and scripting
languages such as PHP, Perl, and more.
If you are interested in our consulting services or want to become a consulting partner, please visit the consulting section of our web site at http://www.mysql.com/consulting/ or contact our consulting staff at consulting@mysql.com.
The MySQL database is released under the
GNU General Public License (GPL).
This means that the MySQL software can be used free of charge
under the GPL. If you do not want to be bound by the GPL
terms (like the requirement that your own application becomes GPL
as well), you may purchase a commercial license for the same product
from MySQL AB.
See http://www.mysql.com/products/pricing.html.
Since MySQL AB owns the copyright to the MySQL source code,
we are able to employ Dual Licensing which means that the same
product is available under GPL and under a commercial
license. This does not in any way affect the Open Source
commitment of MySQL AB. For details about when a commercial
license is required, please see section 1.4.3 MySQL Licenses.
We also sell commercial licenses of third-party Open Source GPL
software that adds value to MySQL Server. A good example is the
InnoDB transactional storage engine that offers ACID
support, row-level locking, crash recovery, multi-versioning, foreign
key support, and more. See section 7.5 InnoDB Tables.
MySQL AB has a worldwide partner programme that covers training
courses, consulting & support, publications plus reselling and
distributing MySQL and related products. MySQL AB Partners
get visibility on the http://www.mysql.com/ web site and the right
to use special versions of the MySQL trademarks to identify their
products and promote their business.
If you are interested in becoming a MySQL AB Partner, please e-mail
partner@mysql.com.
The word MySQL and the MySQL dolphin logo are trademarks of
MySQL AB. See section 1.4.4 MySQL AB Logos and Trademarks.
These trademarks represent a significant value that the MySQL
founders have built over the years.
The MySQL web site (http://www.mysql.com/) is popular among
developers and users. In October 2001, we served 10 million page views.
Our visitors represent a group that makes purchase decisions and
recommendations for both software and hardware. Twelve percent of our
visitors authorise purchase decisions, and only nine percent are not
involved in purchase decisions at all. More than 65% have made one or
more online business purchase within the last half-year, and 70% plan
to make one in the next months.
The MySQL web site (http://www.mysql.com/)
provides the latest information about MySQL and MySQL AB.
For press service and inquiries not covered in our News releases (http://www.mysql.com/news/), please send e-mail to press@mysql.com.
If you have a valid support contract with MySQL AB, you will
get timely, precise answers to your technical questions about the
MySQL software. For more information, see section 1.4.1 Support Offered by MySQL AB.
On our website, see http://www.mysql.com/support/, or send
an e-mail message to sales@mysql.com.
For information about MySQL training, please visit the training
section at http://www.mysql.com/training/. If you have
restricted access to the Internet, please contact the MySQL AB
training staff at training@mysql.com.
See section 1.3.1.2 Training and Certification.
For information on the MySQL Certification Program, please see
http://www.mysql.com/certification/.
See section 1.3.1.2 Training and Certification.
If you're interested in consulting, please visit the consulting
section at http://www.mysql.com/consulting/. If you have
restricted access to the Internet, please contact the MySQL AB
consulting staff at consulting@mysql.com.
See section 1.3.1.3 Consulting.
Commercial licenses may be purchased online at
https://order.mysql.com/. There you will also find information
on how to fax your purchase order to MySQL AB. More information
about licensing can be found at
http://www.mysql.com/products/pricing.html.
If you have
questions regarding licensing or you want a quote for a high-volume
license deal, please fill in the contact form on our web site
(http://www.mysql.com/) or send an e-mail message
to licensing@mysql.com (for licensing questions) or to
sales@mysql.com (for sales inquiries).
See section 1.4.3 MySQL Licenses.
If you represent a business that is interested in partnering with
MySQL AB, please send e-mail to partner@mysql.com.
See section 1.3.1.5 Partnering.
For more information on the MySQL trademark policy, refer to
http://www.mysql.com/company/trademark.html or send e-mail to
trademark@mysql.com.
See section 1.4.4 MySQL AB Logos and Trademarks.
If you are interested in any of the MySQL AB jobs listed in our
jobs section (http://www.mysql.com/company/jobs/),
please send an e-mail message to jobs@mysql.com.
Please do not send your CV as an attachment, but rather as plain text
at the end of your e-mail message.
For general discussion among our many users, please direct your attention to the appropriate mailing list. See section 1.6.1 MySQL Mailing Lists.
Reports of errors (often called bugs), as well as questions and
comments, should be sent to the mailing list at
mysql@lists.mysql.com. If you have found a sensitive
security bug in the MySQL Server, please send an e-mail
to security@mysql.com.
See section 1.6.1.3 How to Report Bugs or Problems.
If you have benchmark results that we can publish, please contact us at benchmarks@mysql.com.
If you have any suggestions concerning additions or corrections to this manual, please send them to the manual team at docs@mysql.com.
For questions or comments about the workings or content of the
MySQL web site (http://www.mysql.com/),
please send e-mail to webmaster@mysql.com.
MySQL AB has a privacy policy, which can be read at
http://www.mysql.com/company/privacy.html.
For any queries regarding this policy, please e-mail
privacy@mysql.com.
For all other inquires, please send e-mail to info@mysql.com.
This section describes MySQL support and licensing arrangements.
Technical support from MySQL AB means individualised answers
to your unique problems direct from the software engineers who code
the MySQL database engine.
We try to take a broad and inclusive view of technical support. Almost
any problem involving MySQL software is important to us if it's
important to you.
Typically customers seek help on how to get different commands and
utilities to work, remove performance bottlenecks, restore crashed
systems, understand operating system or networking impacts on MySQL,
set up best practices for backup and recovery, utilise APIs, etc.
Our support covers only the MySQL server and our own utilities,
not third-party products that access the MySQL server, though we
try to help with these where we can.
Detailed information about our various support options is given at http://www.mysql.com/support/, where support contracts can also be ordered online. If you have restricted access to the Internet, contact our sales staff at sales@mysql.com.
Technical support is like life insurance. You can live happily
without it for years, but when your hour arrives it becomes
critically important, yet it's too late to buy it!
If you use MySQL Server for important applications and encounter
sudden troubles, it might take too long to figure out all the answers
yourself. You may need immediate access to the most experienced
MySQL troubleshooters available, those employed by MySQL AB.
MySQL AB owns the copyright to the MySQL source code,
the MySQL logos and trademarks and this manual.
See section 1.3 What Is MySQL AB?.
Several different licenses are relevant to the MySQL
distribution:
MySQL-specific source in the server, the mysqlclient
library and the client, as well as the GNU readline library
is covered by the GNU General Public License.
See section H GNU General Public License.
The text of this license can also be found as the file `COPYING'
in the distributions.
GNU getopt library is covered by the
GNU Lesser General Public License.
See section I GNU Lesser General Public License.
regexp library) are covered
by a Berkeley-style copyright.
MySQL (3.22 and earlier) are subject to a
more strict license
(http://www.mysql.com/products/mypl.html).
See the documentation of the specific version for information.
GPL-style license.
Use of the manual is subject to the following terms:
MySQL AB is required.
For information about how the MySQL licenses work in practice,
please refer to section 1.4.3 MySQL Licenses.
Also see section 1.4.4 MySQL AB Logos and Trademarks.
The MySQL software is released under the
GNU General Public License (GPL),
which probably is the best known Open Source license.
The formal terms of the GPL license can be found at
http://www.gnu.org/licenses/.
See also http://www.gnu.org/licenses/gpl-faq.html and
http://www.gnu.org/philosophy/enforcing-gpl.html.
Since the MySQL software is released under the GPL,
it may often be used for free, but for certain uses you may want
or need to buy commercial licenses from MySQL AB at
https://order.mysql.com/.
See http://www.mysql.com/products/licensing.html for
more information.
Older versions of MySQL (3.22 and earlier) are subject to a
more strict license
(http://www.mysql.com/products/mypl.html).
See the documentation of the specific version for information.
Please note that the use of the MySQL software under commercial
license, GPL, or the old MySQL license does not
automatically give you the right to use MySQL AB trademarks.
See section 1.4.4 MySQL AB Logos and Trademarks.
The GPL license is contagious in the sense that when a program
is linked to a GPL program all the source code for all the parts
of the resulting product must also be released under the GPL.
Otherwise you break the license terms and forfeit your right to use the
GPL program altogether and also risk damages.
You need a commercial license:
GPL code from the MySQL
software and don't want the resulting product to be GPL, maybe
because you want to build a commercial product or keep the added
non-GPL code closed source for other reasons. When purchasing
commercial licenses, you are not using the MySQL software under
GPL even though it's the same code.
GPL application that only works with the
MySQL software and ship it with the MySQL software. This type
of solution is actually considered to be linking even if it's done over
a network.
MySQL software without providing
the source code as required under the GPL license.
MySQL
database even if you don't formally need a commercial license.
Purchasing support directly from MySQL AB is another good way
of contributing to the development of the MySQL software, with
immediate advantages for you.
See section 1.4.1 Support Offered by MySQL AB.
If you require a license, you will need one for each installation of the
MySQL software. This covers any number of CPUs on a machine, and there
is no artificial limit on the number of clients that connect to the server
in any way.
For commercial licenses, please visit our website at http://www.mysql.com/products/licensing.html. For support contracts, see http://www.mysql.com/support/. If you have special needs or you have restricted access to the Internet, please contact our sales staff at sales@mysql.com.
You can use the MySQL software for free under the GPL if
you adhere to the conditions of the GPL.
For more complete coverage of the common questions about the GPL
see the generic FAQ from the Free Software Foundation at
http://www.gnu.org/licenses/gpl-faq.html.
Some common cases:
MySQL
source code under the GPL with your product.
MySQL source code bundled with other
programs that are not linked to or dependent on the MySQL system
for their functionality even if you sell the distribution commercially.
This is called mere aggregation in the GPL license.
MySQL
system, you can use it for free.
MySQL servers for your customers.
However, we do encourage people to use ISPs that have MySQL support,
as this will give them the confidence that if they have some problem
with the MySQL installation, their ISP will in fact have the
resources to solve the problem for them.
Note that even if an ISP does not have a commercial license for
MySQL Server, they should at least give their customers read
access to the source of the MySQL installation so that the
customers can verify that it is patched correctly.
MySQL Database Software in conjunction with a
web server, you do not need a commercial license (so long as it is not
a product you distribute). This is true even if you run a commercial
web server that uses MySQL Server, because you are not
distributing any part of the MySQL system. However, in this
case we would like you to purchase MySQL support because the
MySQL software is helping your enterprise.
If your use of MySQL database software does not require a commercial
license, we encourage you to purchase support from MySQL AB anyway.
This way you contribute toward MySQL development and also gain
immediate advantages for yourself. See section 1.4.1 Support Offered by MySQL AB.
If you use the MySQL database software in a commercial context
such that you profit by its use, we ask that you further the development
of the MySQL software by purchasing some level of support. We feel
that if the MySQL database helps your business, it is reasonable to
ask that you help MySQL AB.
(Otherwise, if you ask us support questions, you are not only using
for free something into which we've put a lot a work, you're asking
us to provide free support, too.)
Many users of the MySQL database want to display the
MySQL AB dolphin logo on their web sites, books, or
boxed products. We welcome and encourage this, although it should be
noted that the word MySQL and the MySQL dolphin logo
are trademarks of MySQL AB and may only be used as stated in
our trademark policy at
http://www.mysql.com/company/trademark.html.
The MySQL dolphin logo was designed by the Finnish advertising
agency Priority in 2001. The dolphin was chosen as a suitable symbol
for the MySQL database since it is a smart, fast, and lean animal,
effortlessly navigating oceans of data. We also happen to like dolphins.
The original MySQL logo may only be used by representatives of
MySQL AB and by those having a written agreement allowing them
to do so.
We have designed a set of special Conditional Use logos that may be
downloaded from our web site at
http://www.mysql.com/press/logos.html
and used on third-party web sites without written permission from
MySQL AB.
The use of these logos is not entirely unrestricted but, as the name
implies, subject to our trademark policy that is also available on our
web site. You should read through the trademark policy if you plan to
use them. The requirements are basically:
MySQL AB, are the creator and
owner of the site that displays the MySQL trademark.
MySQL AB
or to the value of MySQL AB trademarks. We reserve the right to
revoke the right to use the MySQL AB trademark.
MySQL database under GPL in an
application, your application must be Open Source and
be able to connect to a MySQL server.
Contact us at trademark@mysql.com to inquire about special arrangements to fit your needs.
In the following cases you need a written permission from MySQL AB
before using MySQL logos:
MySQL AB logo anywhere except on your web site.
MySQL AB logo except the Conditional Use
logos mentioned previously on web sites or elsewhere.
Out of legal and commercial reasons we have to monitor the use of MySQL
trademarks on products, books, etc. We will usually require a fee for
displaying MySQL AB logos on commercial products, since we think
it is reasonable that some of the revenue is returned to fund further
development of the MySQL database.
MySQL partnership logos may only be used by companies and persons
having a written partnership agreement with MySQL AB. Partnerships
include certification as a MySQL trainer or consultant.
Please see section 1.3.1.5 Partnering.
MySQL in Printed Text or Presentations
MySQL AB welcomes references to the MySQL database, but
note that the word MySQL is a trademark of MySQL AB.
Because of this, you should append the trademark symbol (TM) to
the first or most prominent use of the word MySQL in a text and
where appropriate, state that MySQL is a trademark of
MySQL AB. Please refer to our trademark policy at
http://www.mysql.com/company/trademark.html for details.
MySQL in Company and Product Names
Use of the word MySQL in product or company names or in Internet
domain names is not allowed without written permission from MySQL AB.
Long promised by MySQL AB and long awaited by our users,
MySQL Server 4.0 is now available in beta version for download from
http://www.mysql.com/ and our mirrors.
Main new features of MySQL Server 4.0 are geared toward our existing business and community users, enhancing the MySQL database software as the solution for mission-critical, heavy-load database systems. Other new features target the users of embedded databases.
MySQL is starting from 4.0.6 been labelled gamma, which means that 4.0.x has been available more than 2 months (first in alpha and then in beta) without any found serious hard to fix bugs and should now be ready for production use.
We will drop the gamma prefix when MySQL 4.0 has been out for more than a month without any serious bugs.
Further new features are being added in MySQL 4.1, which is now available from our bk source tree, and is targeted for alpha release in first quarter of 2003. See section 2.3.4 Installing from the Development Source Tree.
All binary releases pass our extensive test suite without any errors on any of the platforms we test on. MySQL 4.0 has been tested on by a large number of users and is in production used by several big sites.
libmysqld makes MySQL Server suitable for a vastly expanded realm of
applications. Using the embedded MySQL server library, one can
embed MySQL Server into various applications and electronics devices, where
the end user has no knowledge of there actually being an underlying
database. Embedded MySQL Server is ideal for use behind
the scenes in Internet appliances, public kiosks, turnkey
hardware/software combination units, high performance Internet
servers, self-contained databases distributed on CD-ROM, etc.
Many users of libmysqld will benefit from the MySQL
Dual Licensing. For those not wishing to be bound by the GPL,
the software is also made available under a commercial license.
The embedded MySQL library uses the same interface as the normal
client library, so it is convenient and easy to use. See section 8.4.9 libmysqld, the Embedded MySQL Server Library.
INSERTs, searching on packed indexes, creation of
FULLTEXT indexes, as well as COUNT(DISTINCT).
InnoDB storage engine is now offered as a feature of the
standard MySQL server, including full support for transactions
and row-level locking.
latin1_de, which corrects the German sorting order,
placing German umlauts in the same order as German telephone books.
TRUNCATE TABLE (like in Oracle) and IDENTITY as a
synonym for automatically incremented keys (like in Sybase). Many users will
also be happy to learn that MySQL Server now supports the UNION statement,
a long-awaited standard SQL feature.
DELETE and UPDATE statements.
By adding support for symbolic linking to MyISAM on the table
level (and not just the database level as before), as well as by enabling symlink
handling by default on Windows, we hope to show that we take enhancement
requests seriously.
Functions like SQL_CALC_FOUND_ROWS and FOUND_ROWS() make it
possible to know how many rows a query would have returned without a
LIMIT clause.
For the upcoming MySQL Server 4.x releases, expect the following features now still under development:
fail-safe replication;
already existing in 4.0, the LOAD DATA FROM MASTER command
will soon automate slave setup. The online backup will make
it easy to add a new replication slave without taking down
the master, and have a very low performance penalty on
update-heavy systems.
mysqld parameters (startup options) can soon be set without
taking down the servers.
FULLTEXT search properties of MySQL Server 4.0 enable the
use of FULLTEXT indexing of large text masses with both binary and
natural-language searching logic. Users can customise minimal word
length and define their own stop word lists in any human language,
enabling a new set of applications to be built on MySQL Server.
key cache.
MySQL command help
in the client.
MySQL Server 4.0 lays the foundation for the new features of
MySQL Server 4.1 and onward, such as nested subqueries (4.1),
stored procedures (5.0), and
foreign key integrity rules for MyISAM tables (5.0),
which form the top of the wish list for many of our customers.
After those additions, critics of the MySQL Database Server have to be more imaginative than ever in pointing out deficiencies in the MySQL Database Management System. For long already known for its stability, speed, and ease of use, MySQL Server will then match the requirement checklist of very demanding buyers.
This section introduces you to the MySQL mailing lists, and gives some guidelines as to how to use them. By subscribing to a mailing list, you will receive as e-mail messages all other postings on the list, and you will be able to send in your own questions and answers.
To subscribe to the main MySQL mailing list, send a message to the electronic mail address mysql-subscribe@lists.mysql.com.
To unsubscribe from the main MySQL mailing list, send a message to the electronic mail address mysql-unsubscribe@lists.mysql.com.
Only the address to which you send your messages is significant. The subject line and the body of the message are ignored.
If your reply address is not valid, you can specify your address
explicitly, by adding a hyphen to the subscribe or unsubscribe command
word, followed by your address with the `@' character in your
address replaced by a `='. For example, to subscribe
your_name@host.domain, send a message to
mysql-subscribe-your_name=host.domain@lists.mysql.com.
Mail to mysql-subscribe@lists.mysql.com or mysql-unsubscribe@lists.mysql.com is handled automatically by the ezmlm mailing list processor. Information about ezmlm is available at the ezmlm web site (http://www.ezmlm.org/).
To post a message to the list itself, send your message to
mysql@lists.mysql.com. However, please do not send mail about
subscribing or unsubscribing to mysql@lists.mysql.com because any
mail sent to that address is distributed automatically to thousands of other
users.
Your local site may have many subscribers to mysql@lists.mysql.com.
If so, it may have a local mailing list, so messages sent from
lists.mysql.com to your site are propagated to the local list. In such
cases, please contact your system administrator to be added to or dropped
from the local MySQL list.
If you wish to have traffic for a mailing list go to a separate mailbox in
your mail program, set up a filter based on the message headers. You can
use either the List-ID: or Delivered-To: headers to identify
list messages.
The following MySQL mailing lists exist:
announce-subscribe@lists.mysql.com announce
mysql-subscribe@lists.mysql.com mysql
mysql-digest-subscribe@lists.mysql.com mysql-digest
mysql list in digest form. That means you get all individual
messages, sent as one large mail message once a day.
bugs-subscribe@lists.mysql.com bugs
mysqlbug script (if you are running on Windows, you should
include a description of the operating system and the MySQL version).
Preferably, you should test the problem using the latest stable or development
version of MySQL Server before posting! Anyone should be able to repeat the
bug by just using mysql test < script on the included test case. All
bugs posted on this list will be corrected or documented in the next
MySQL release! If only small code changes are needed, we
will also post a patch that fixes the problem.
bugs-digest-subscribe@lists.mysql.com bugs-digest
bugs list in digest form.
internals-subscribe@lists.mysql.com internals
internals-digest-subscribe@lists.mysql.com internals-digest
internals list.
java-subscribe@lists.mysql.com java
java-digest-subscribe@lists.mysql.com java-digest
java list.
win32-subscribe@lists.mysql.com win32
win32-digest-subscribe@lists.mysql.com win32-digest
win32 list.
myodbc-subscribe@lists.mysql.com myodbc
myodbc-digest-subscribe@lists.mysql.com myodbc-digest
myodbc list.
mysqlcc-subscribe@lists.mysql.com mysqlcc
MySQL Control Center graphical client.
mysqlcc-digest-subscribe@lists.mysql.com mysqlcc-digest
mysqlcc list.
plusplus-subscribe@lists.mysql.com plusplus
plusplus-digest-subscribe@lists.mysql.com plusplus-digest
plusplus list.
msql-mysql-modules-subscribe@lists.mysql.com msql-mysql-modules
msql-mysql-modules-digest-subscribe@lists.mysql.com msql-mysql-modules-digest
msql-mysql-modules list.
You subscribe or unsubscribe to all lists in the same way as described
previously. In your subscribe or unsubscribe message, just put the appropriate
mailing list name rather than mysql. For example, to subscribe to or
unsubscribe from the myodbc list, send a message to
myodbc-subscribe@lists.mysql.com or
myodbc-unsubscribe@lists.mysql.com.
If you can't get an answer for your questions from the mailing list, one option is to pay for support from MySQL AB, which will put you in direct contact with MySQL developers. See section 1.4.1 Support Offered by MySQL AB.
The following table shows some MySQL mailing in languages other than English. Note that these are not operated by MySQL AB, so we can't guarantee the quality on these.
mysql-france-subscribe@yahoogroups.com A French mailing list
list@tinc.net A Korean mailing list
subscribe mysql your@e-mail.address to this list.
mysql-de-request@lists.4t2.com A German mailing list
subscribe mysql-de your@e-mail.address to this list.
You can find information about this mailing list at
http://www.4t2.com/mysql/.
mysql-br-request@listas.linkway.com.br A Portugese mailing list
subscribe mysql-br your@e-mail.address to this list.
mysql-alta@elistas.net A Spanish mailing list
subscribe mysql your@e-mail.address to this list.
Before posting a bug report or question, please do the following:
If you can't find an answer in the manual or the archives, check with your local MySQL expert. If you still can't find an answer to your question, go ahead and read the next section about how to send mail to mysql@lists.mysql.com.
Writing a good bug report takes patience, but doing it right the first time saves time for us and for you. A good bug report containing a full test case for the bug will make it very likely that we will fix it in the next release. This section will help you write your report correctly so that you don't waste your time doing things that may not help us much or at all.
We encourage everyone to use the mysqlbug script to generate a bug
report (or a report about any problem), if possible. mysqlbug can be
found in the `scripts' directory in the source distribution, or for a
binary distribution, in the `bin' directory under your MySQL
installation directory. If you are unable to use mysqlbug, you should
still include all the necessary information listed in this section.
The mysqlbug script helps you generate a report by determining much
of the following information automatically, but if something important is
missing, please include it with your message! Please read this section
carefully and make sure that all the information described here is included
in your report.
The normal place to report bugs and problems is
mysql@lists.mysql.com. If you can make a test case that clearly
demonstrates the bug, you should post it to the bugs@lists.mysql.com
list. Note that on this list you should only post a full, repeatable bug
report using the mysqlbug script. If you are running on Windows,
you should include a description of the operating system and the
MySQL version. Preferably, you should test the problem using
the latest stable or development version of MySQL Server before
posting! Anyone should be able to repeat the bug by just using
``mysql test < script'' on the included test case or run the
shell or Perl script that is included in the bug report. All bugs
posted on the bugs list will be corrected or documented in the next
MySQL release! If only small code changes are needed
to correct this problem, we will also post a patch that fixes the
problem.
If you have found a sensitive security bug in MySQL, you should send an e-mail to security@mysql.com.
Remember that it is possible to respond to a message containing too much information, but not to one containing too little. Often people omit facts because they think they know the cause of a problem and assume that some details don't matter. A good principle is: if you are in doubt about stating something, state it! It is a thousand times faster and less troublesome to write a couple of lines more in your report than to be forced to ask again and wait for the answer because you didn't include enough information the first time.
The most common errors are that people don't indicate the version number of the MySQL distribution they are using, or don't indicate what platform they have the MySQL server installed on (including the platform version number). This is highly relevant information, and in 99 cases out of 100 the bug report is useless without it! Very often we get questions like, ``Why doesn't this work for me?'' Then we find that the feature requested wasn't implemented in that MySQL version, or that a bug described in a report has been fixed already in newer MySQL versions. Sometimes the error is platform-dependent; in such cases, it is next to impossible to fix anything without knowing the operating system and the version number of the platform.
Remember also to provide information about your compiler, if it is related to the problem. Often people find bugs in compilers and think the problem is MySQL-related. Most compilers are under development all the time and become better version by version. To determine whether your problem depends on your compiler, we need to know what compiler is used. Note that every compiling problem should be regarded as a bug report and reported accordingly.
It is most helpful when a good description of the problem is included in the bug report. That is, a good example of all the things you did that led to the problem and the problem itself exactly described. The best reports are those that include a full example showing how to reproduce the bug or problem. See section E.1.6 Making a Test Case When You Experience Table Corruption.
If a program produces an error message, it is very important to include the message in your report! If we try to search for something from the archives using programs, it is better that the error message reported exactly matches the one that the program produces. (Even the case should be observed!) You should never try to remember what the error message was; instead, copy and paste the entire message into your report!
If you have a problem with MyODBC, you should try to generate a MyODBC trace file. See section 8.3.7 Reporting Problems with MyODBC.
Please remember that many of the people who will read your report will
do so using an 80-column display. When generating reports or examples
using the mysql command-line tool, you should therefore use
the --vertical option (or the \G statement terminator)
for output that would exceed the available width for such a display
(for example, with the EXPLAIN SELECT statement; see the
example later in this section).
Please include the following information in your report:
mysqladmin version. mysqladmin can be
found in the `bin' directory under your MySQL installation
directory.
uname -a.
mysqld died, you should also report the query that crashed
mysqld. You can usually find this out by running mysqld with
logging enabled. See section E.1.5 Using Log Files to Find Cause of Errors in mysqld.
mysqldump --no-data db_name tbl_name1 tbl_name2 .... This is very easy
to do and is a powerful way to get information about any table in a database
that will help us create a situation matching the one you have.
SELECT statements, you
should always include the output of EXPLAIN SELECT ..., and at
least the number of rows that the SELECT statement produces. You
should also include the output from SHOW CREATE TABLE table_name
for each involved table. The more information you give about your
situation, the more likely it is that someone can help you! For
example, the following is an example of a very good bug report (it
should of course be posted with the mysqlbug script):
Example run using the mysql command-line tool (note the use of the
\G statement terminator for statements whose output width would
otherwise exceed that of an 80-column display device):
mysql> SHOW VARIABLES;
mysql> SHOW COLUMNS FROM ...\G
<output from SHOW COLUMNS>
mysql> EXPLAIN SELECT ...\G
<output from EXPLAIN>
mysql> FLUSH STATUS;
mysql> SELECT ...;
<A short version of the output from SELECT,
including the time taken to run the query>
mysql> SHOW STATUS;
<output from SHOW STATUS>
mysqld, try to provide an
input script that will reproduce the anomaly. This script should include any
necessary source files. The more closely the script can reproduce your
situation, the better. If you can make a reproduceable test case, you should
post this to bugs@lists.mysql.com for a high-priority treatment!
If you can't provide a script, you should at least include the output
from mysqladmin variables extended-status processlist in your mail to
provide some information of how your system is performing!
mysqldump and create a `README' file
that describes your problem.
Create a compressed archive of your files using
tar and gzip or zip, and use ftp to transfer the
archive to ftp://support.mysql.com/pub/mysql/secret/. Then send a
short description of the problem to bugs@lists.mysql.com.
ftp to transfer it to
ftp://support.mysql.com/pub/mysql/secret/. If the data is really top
secret and you don't want to show it even to us, then go ahead and provide
an example using other names, but please regard this as the last choice.
mysqld
daemon and that you use to run any MySQL client programs. The
options to programs like mysqld and mysql, and to the
configure script, are often keys to answers and are very relevant!
It is never a bad idea to include them anyway! If you use any modules, such
as Perl or PHP, please include the version number(s) of those as well.
mysqlaccess, the output of mysqladmin reload, and all
the error messages you get when trying to connect! When you test your
privileges, you should first run mysqlaccess. After this, execute
mysqladmin reload version and try to connect with the program that
gives you trouble. mysqlaccess can be found in the `bin'
directory under your MySQL installation directory.
parse error, please check your syntax closely! If
you can't find something wrong with it, it's extremely likely that your
current version of MySQL Server doesn't support the query you are
using. If you are using the current version and the manual at
http://www.mysql.com/doc/ doesn't cover the
syntax you are using, MySQL Server doesn't support your query. In this
case, your only options are to implement the syntax yourself or e-mail
licensing@mysql.com and ask for an offer to implement it!
If the manual covers the syntax you are using, but you have an older version
of MySQL Server, you should check the MySQL change history to see
when the syntax was implemented. In this case, you have the option of
upgrading to a newer version of MySQL Server. See section D MySQL Change History.
myisamchk or CHECK TABLE and
REPAIR TABLE. See section 4 Database Administration.
mysqld should never crash a table if nothing killed it in the
middle of an update! If you can find the cause of mysqld dying,
it's much easier for us to provide you with a fix for the problem.
See section A.1 How to Determine What Is Causing Problems.
If you are a support customer, please cross-post the bug report to mysql-support@mysql.com for higher-priority treatment, as well as to the appropriate mailing list to see if someone else has experienced (and perhaps solved) the problem.
For information on reporting bugs in MyODBC, see section 8.3.4 How to Report Problems with MyODBC.
For solutions to some common problems, see section A Problems and Common Errors.
When answers are sent to you individually and not to the mailing list, it is considered good etiquette to summarise the answers and send the summary to the mailing list so that others may have the benefit of responses you received that helped you solve your problem!
If you consider your answer to have broad interest, you may want to post it to the mailing list instead of replying directly to the individual who asked. Try to make your answer general enough that people other than the original poster may benefit from it. When you post to the list, please make sure that your answer is not a duplication of a previous answer.
Try to summarise the essential part of the question in your reply; don't feel obliged to quote the entire original message.
Please don't post mail messages from your browser with HTML mode turned on! Many users don't read mail with a browser!
In addition to the various MySQL mailing lists, you can find experienced
community people on IRC (Internet Relay Chat).
These are the best networks/channels currently known to us:
#mysql
Primarily MySQL questions but other database and SQL questions welcome.
#mysqlphp
Questions about MySQL+PHP, a popular combo.
#mysql
MySQL questions.
If you are looking for IRC client software to connect to an IRC network,
take a peek at X-Chat (http://www.xchat.org/).
X-Chat is available for Unix as well as for Windows platforms.
This section describes how MySQL relates to the ANSI SQL standards. MySQL Server has many extensions to the ANSI SQL standards, and here you will find out what they are and how to use them. You will also find information about functionality missing from MySQL Server, and how to work around some differences.
Our goal is to not, without a very good reason, restrict MySQL Server usability for any usage. Even if we don't have the resources to do development for every possible use, we are always willing to help and offer suggestions to people who are trying to use MySQL Server in new territories.
One of our main goals with the product is to continue to work toward
ANSI 99 compliancy, but without sacrificing speed or reliability.
We are not afraid to add extensions to SQL or support for non-SQL
features if this greatly increases the usability of MySQL Server for a big
part of our users. (The new HANDLER interface in MySQL Server 4.0
is an example of this strategy. See section 6.4.2 HANDLER Syntax.)
We will continue to support transactional and non-transactional databases to satisfy both heavy web/logging usage and mission-critical 24/7 usage.
MySQL Server was designed from the start to work with medium size databases (10-100 million rows, or about 100 MB per table) on small computer systems. We will continue to extend MySQL Server to work even better with terabyte-size databases, as well as to make it possible to compile a reduced MySQL version that is more suitable for hand-held devices and embedded usage. The compact design of the MySQL server makes both of these directions possible without any conflicts in the source tree.
We are currently not targeting realtime support or clustered databases (even if you can already do a lot of things with our replication services).
We don't believe that one should have native XML support in the database, but will instead add the XML support our users request from us on the client side. We think it's better to keep the main server code as ``lean and clean'' as possible and instead develop libraries to deal with the complexity on the client side. This is part of the strategy mentioned previously of not sacrificing speed or reliability in the server.
Entry-level SQL92. ODBC levels 0-3.51.
We are aiming toward supporting the full ANSI SQL99 standard, but without concessions to speed and quality of the code.
If you start mysqld with the --ansi option, the following
behaviour of MySQL Server changes:
|| is string concatenation instead of OR.
REAL will be a synonym for FLOAT instead of a synonym for
DOUBLE.
SERIALIZABLE.
See section 6.7.3 SET TRANSACTION Syntax.
GROUP BY that is not in the
field list.
This is the same as using
--sql-mode=REAL_AS_FLOAT,PIPES_AS_CONCAT,ANSI_QUOTES,
IGNORE_SPACE,SERIALIZE,ONLY_FULL_GROUP_BY.
MySQL Server includes some extensions that you probably will not find in
other SQL databases. Be warned that if you use them, your code will not be
portable to other SQL servers. In some cases, you can write code that
includes MySQL extensions, but is still portable, by using comments
of the form /*! ... */. In this case, MySQL Server will parse and
execute the code within the comment as it would any other MySQL
statement, but other SQL servers will ignore the extensions. For example:
SELECT /*! STRAIGHT_JOIN */ col_name FROM table1,table2 WHERE ...
If you add a version number after the '!', the syntax will be
executed only if the MySQL version is equal to or newer than the used
version number:
CREATE /*!32302 TEMPORARY */ TABLE t (a int);
This means that if you have Version 3.23.02 or newer, MySQL
Server will use the TEMPORARY keyword.
The following is a list of MySQL extensions:
MEDIUMINT, SET, ENUM, and the
different BLOB and TEXT types.
AUTO_INCREMENT, BINARY, NULL,
UNSIGNED, and ZEROFILL.
BINARY attribute or use the BINARY cast, which causes
comparisons to be done according to the ASCII order used on the
MySQL server host.
db_name.tbl_name syntax. Some SQL servers provide
the same functionality but call this User space.
MySQL Server doesn't support tablespaces as in:
create table ralph.my_table...IN my_tablespace.
LIKE is allowed on numeric columns.
INTO OUTFILE and STRAIGHT_JOIN in a SELECT
statement. See section 6.4.1 SELECT Syntax.
SQL_SMALL_RESULT option in a SELECT statement.
EXPLAIN SELECT to get a description on how tables are joined.
INDEX or KEY in a CREATE TABLE
statement. See section 6.5.3 CREATE TABLE Syntax.
TEMPORARY or IF NOT EXISTS with CREATE TABLE.
COUNT(DISTINCT list) where list is more than one element.
CHANGE col_name, DROP col_name, or DROP
INDEX, IGNORE or RENAME in an ALTER TABLE
statement. See section 6.5.4 ALTER TABLE Syntax.
RENAME TABLE. See section 6.5.5 RENAME TABLE Syntax.
ADD, ALTER, DROP, or CHANGE
clauses in an ALTER TABLE statement.
DROP TABLE with the keywords IF EXISTS.
DROP TABLE statement.
LIMIT clause of the DELETE statement.
DELAYED clause of the INSERT and REPLACE
statements.
LOW_PRIORITY clause of the INSERT, REPLACE,
DELETE, and UPDATE statements.
LOAD DATA INFILE. In many cases, this syntax is compatible with
Oracle's LOAD DATA INFILE. See section 6.4.9 LOAD DATA INFILE Syntax.
ANALYZE TABLE, CHECK TABLE, OPTIMIZE TABLE, and
REPAIR TABLE statements.
SHOW statement.
See section 4.5.6 SHOW Syntax.
SET statement. See section 5.5.6 SET Syntax.
GROUP BY part.
This gives better performance for some very specific, but quite normal
queries.
See section 6.3.7 Functions for Use with GROUP BY Clauses.
ASC and DESC with GROUP BY.
|| and && operators to mean
logical OR and AND, as in the C programming language. In MySQL Server,
|| and OR are synonyms, as are && and AND.
Because of this nice syntax, MySQL Server doesn't support
the ANSI SQL || operator for string concatenation; use
CONCAT() instead. Because CONCAT() takes any number
of arguments, it's easy to convert use of the || operator to
MySQL Server.
CREATE DATABASE or DROP DATABASE.
See section 6.5.1 CREATE DATABASE Syntax.
% operator is a synonym for MOD(). That is,
N % M is equivalent to MOD(N,M). % is supported
for C programmers and for compatibility with PostgreSQL.
=, <>, <= ,<, >=,>,
<<, >>, <=>, AND, OR, or LIKE
operators may be used in column comparisons to the left of the
FROM in SELECT statements. For example:
mysql> SELECT col1=1 AND col2=2 FROM tbl_name;
LAST_INSERT_ID() function.
See section 8.4.3.130 mysql_insert_id().
REGEXP and NOT REGEXP extended regular expression
operators.
CONCAT() or CHAR() with one argument or more than two
arguments. (In MySQL Server, these functions can take any number of
arguments.)
BIT_COUNT(), CASE, ELT(),
FROM_DAYS(), FORMAT(), IF(), PASSWORD(),
ENCRYPT(), MD5(), ENCODE(), DECODE(),
PERIOD_ADD(), PERIOD_DIFF(), TO_DAYS(), or
WEEKDAY() functions.
TRIM() to trim substrings. ANSI SQL only supports removal
of single characters.
GROUP BY functions STD(), BIT_OR(), and
BIT_AND().
REPLACE instead of DELETE + INSERT.
See section 6.4.8 REPLACE Syntax.
FLUSH, RESET and DO statements.
:=:
SELECT @a:=SUM(total),@b=COUNT(*),@a/@b AS avg FROM test_table; SELECT @t1:=(@t2:=1)+@t3:=4,@t1,@t2,@t3;
We try to make MySQL Server follow the ANSI SQL standard and the ODBC SQL standard, but in some cases MySQL Server does things differently:
VARCHAR columns, trailing spaces are removed when the value is
stored. See section 1.7.5 Known Errors and Design Deficiencies in MySQL.
CHAR columns are silently changed to VARCHAR
columns. See section 6.5.3.1 Silent Column Specification Changes.
REVOKE to revoke privileges for
a table. See section 4.3.1 GRANT and REVOKE Syntax.
NULL AND FALSE will evaluate to NULL and not to FALSE.
This is because we don't think it's good to have to evaluate a lot of
extra conditions in this case.
For a prioritised list indicating when new extensions will be added to MySQL Server, you should consult the online MySQL TODO list at http://www.mysql.com/doc/en/TODO.html. That is the latest version of the TODO list in this manual. See section 1.8 MySQL and The Future (The TODO).
SELECTs
MySQL Server until version 4.0 only supports nested queries of the form
INSERT ... SELECT ... and REPLACE ... SELECT ....
You can, however, use the function IN() in other contexts.
Subqueries have been implemented in the 4.1 development tree.
Meanwhile, you can often rewrite the query without a subquery:
SELECT * FROM table1 WHERE id IN (SELECT id FROM table2);
This can be rewritten as:
SELECT table1.* FROM table1,table2 WHERE table1.id=table2.id;
The queries:
SELECT * FROM table1 WHERE id NOT IN (SELECT id FROM table2);
SELECT * FROM table1 WHERE NOT EXISTS (SELECT id FROM table2
WHERE table1.id=table2.id);
Can be rewritten as:
SELECT table1.* FROM table1 LEFT JOIN table2 ON table1.id=table2.id
WHERE table2.id IS NULL;
For more complicated subqueries you can often create temporary tables
to hold the subquery. In some cases, however, this option will not
work. The most frequently encountered of these cases arises with
DELETE statements, for which standard SQL does not support joins
(except in subqueries). For this situation there are two options
available until subqueries are supported by MySQL Server.
The first option is to use a procedural programming language (such as
Perl or PHP) to submit a SELECT query to obtain the primary keys
for the records to be deleted, and then use these values to construct
the DELETE statement (DELETE FROM ... WHERE ... IN (key1,
key2, ...)).
The second option is to use interactive SQL to construct a set of
DELETE statements automatically, using the MySQL
extension CONCAT() (in lieu of the standard || operator).
For example:
SELECT CONCAT('DELETE FROM tab1 WHERE pkid = ', "'", tab1.pkid, "'", ';')
FROM tab1, tab2
WHERE tab1.col1 = tab2.col2;
You can place this query in a script file and redirect input from it to
the mysql command-line interpreter, piping its output back to a
second instance of the interpreter:
shell> mysql --skip-column-names mydb < myscript.sql | mysql mydb
MySQL Server 4.0 supports multi-table deletes that can be used to efficiently delete rows based on information from one table or even from many tables at the same time.
SELECT INTO TABLE
MySQL Server doesn't yet support the Oracle SQL extension:
SELECT ... INTO TABLE .... MySQL Server supports instead the
ANSI SQL syntax INSERT INTO ... SELECT ..., which is basically
the same thing. See section 6.4.3.1 INSERT ... SELECT Syntax.
INSERT INTO tblTemp2 (fldID) SELECT tblTemp1.fldOrder_ID
FROM tblTemp1 WHERE tblTemp1.fldOrder_ID > 100;
Alternatively, you can use SELECT INTO OUTFILE... or CREATE
TABLE ... SELECT.
MySQL Server supports transactions with the InnoDB and BDB
Transactional table handlers. See section 7 MySQL Table Types.
InnoDB provides ACID compliancy.
However, the non-transactional table types in MySQL Server such as
MyISAM follow another paradigm for data integrity called
``Atomic Operations.'' Atomic operations often offer equal or
even better integrity with much better performance.
With MySQL Server supporting both paradigms, the user is able to decide if
he needs the speed of atomic operations or if he need to use
transactional features in his applications. This choice can be made
on a per-table basis.
How does one use the features of MySQL Server to maintain rigorous integrity and how do these features compare with the transactional paradigm?
ROLLBACK instead of
COMMIT in critical situations, transactions are more
convenient. Transactions also ensure that unfinished updates or
corrupting activities are not committed to the database; the server is
given the opportunity to do an automatic rollback and your database is
saved.
MySQL Server, in almost all cases, allows you to resolve potential problems
by including simple checks before updates and by running simple scripts
that check the databases for inconsistencies and automatically repair
or warn if such an inconsistency occurs. Note that just by using the
MySQL log or even adding one extra log, one can normally fix tables
perfectly with no data integrity loss.
LOCK TABLES or atomic updates, ensuring
that you never will get an automatic abort from the database, which is
a common problem with transactional databases.
The transactional paradigm has its benefits and its drawbacks. Many users and application developers depend on the ease with which they can code around problems where an abort appears to be, or is necessary. However, even if you are new to the atomic operations paradigm, or more familiar with transactions, do consider the speed benefit that non-transactional tables can offer on the order of three to five times the speed of the fastest and most optimally tuned transactional tables.
In situations where integrity is of highest importance, MySQL Server offers
transaction-level or better reliability and integrity even for
non-transactional tables.
If you lock tables with LOCK TABLES, all updates will stall
until any integrity checks are made. If you only obtain a read lock
(as opposed to a write lock), reads and inserts are still allowed
to happen. The new inserted records will not be seen by any of the
clients that have a read lock until they release their read
locks. With INSERT DELAYED you can queue inserts into a local
queue, until the locks are released, without having the client wait
for the insert to complete. See section 6.4.4 INSERT DELAYED Syntax.
``Atomic,'' in the sense that we mean it, is nothing magical. It only means that you can be sure that while each specific update is running, no other user can interfere with it, and there will never be an automatic rollback (which can happen with transactional tables if you are not very careful). MySQL Server also guarantees that there will not be any dirty reads.
Following are some techniques for working with non-transactional tables:
LOCK TABLES, and you don't need cursors when you can update
records on the fly.
ROLLBACK, you can use the following strategy:
LOCK TABLES ... to lock all the tables you want to access.
UNLOCK TABLES to release your locks.
ROLLBACKs, although not always. The only situation
this solution doesn't handle is when someone kills the threads in the
middle of an update. In this case, all locks will be released but some
of the updates may not have been executed.
WHERE clause in the UPDATE statement. If the record wasn't
updated, we give the client a message: "Some of the data you have changed
has been changed by another user." Then we show the old row versus the new
row in a window, so the user can decide which version of the customer record
he should use.
This gives us something that is similar to column locking but is actually
even better because we only update some of the columns, using values that
are relative to their current values. This means that typical UPDATE
statements look something like these:
UPDATE tablename SET pay_back=pay_back+'relative change';
UPDATE customer
SET
customer_date='current_date',
address='new address',
phone='new phone',
money_he_owes_us=money_he_owes_us+'new_money'
WHERE
customer_id=id AND address='old address' AND phone='old phone';
As you can see, this is very efficient and works even if another client
has changed the values in the pay_back or money_he_owes_us
columns.
ROLLBACK and/or LOCK
TABLES for the purpose of managing unique identifiers for some tables.
This can be handled much more efficiently by using an
AUTO_INCREMENT column and either the SQL function
LAST_INSERT_ID() or the C API function mysql_insert_id().
See section 8.4.3.130 mysql_insert_id().
You can generally code around row-level locking. Some situations really
need it, but they are very few. InnoDB tables support row-level
locking. With MyISAM, you can use a flag column in the table and do
something like the following:
UPDATE tbl_name SET row_flag=1 WHERE id=ID;MySQL returns 1 for the number of affected rows if the row was found and
row_flag wasn't already 1 in the original row.
You can think of it as though MySQL Server changed the preceding query to:
UPDATE tbl_name SET row_flag=1 WHERE id=ID AND row_flag <> 1;
A stored procedure is a set of SQL commands that can be compiled and stored in the server. Once this has been done, clients don't need to keep re-issuing the entire query but can refer to the stored procedure. This provides better performance because the query has to be parsed only once, and less information needs to be sent between the server and the client. You can also raise the conceptual level by having libraries of functions in the server.
A trigger is a stored procedure that is invoked when a particular event occurs. For example, you can install a stored procedure that is triggered each time a record is deleted from a transaction table and that automatically deletes the corresponding customer from a customer table when all his transactions are deleted.
The planned update language will be able to handle stored procedures. Our aim is to have stored procedures implemented in MySQL Server around version 5.0. We are also looking at triggers.
Note that foreign keys in SQL are not used to join tables, but are used
mostly for checking referential integrity (foreign key constraints). If
you want to get results from multiple tables from a SELECT
statement, you do this by joining tables:
SELECT * FROM table1,table2 WHERE table1.id = table2.id;
See section 6.4.1.1 JOIN Syntax. See section 3.5.6 Using Foreign Keys.
In MySQL Server 3.23.44 and up, InnoDB tables support checking of
foreign key constraints. See section 7.5 InnoDB Tables. For other table types, MySQL Server
does parse the FOREIGN KEY syntax in CREATE TABLE
commands, but without further action being taken.
The FOREIGN KEY syntax without ON DELETE ... is mostly
used for documentation purposes. Some ODBC applications may use this
to produce automatic WHERE clauses, but this is usually easy to
override. FOREIGN KEY is sometimes used as a constraint check,
but this check is unnecessary in practice if rows are inserted into the
tables in the right order.
In MySQL Server, you can work around the problem of ON DELETE ... not
being implemented by adding the appropriate DELETE statement to
an application when you delete records from a table that has a foreign
key. In practice this is as quick (in some cases quicker) and much more
portable than using foreign keys.
In MySQL Server 4.0 you can use multi-table delete to delete rows from many
tables with one command. See section 6.4.6 DELETE Syntax.
In the near future we will extend the FOREIGN KEY implementation
so that the information will be saved in the table specification file
and may be retrieved by mysqldump and ODBC. At a later stage we
will implement the foreign key constraints for applications that can't
easily be coded to avoid them.
Do keep in mind that foreign keys are often misused, which can cause severe problems. Even when used properly, it is not a magic solution for the referential integrity problem, although it does make things easier in some cases.
Some advantages of foreign key enforcement:
Disadvantages:
It is planned to implement views in MySQL Server around version 5.0.
Views are mostly useful for letting users access a set of relations as one table (in read-only mode). Many SQL databases don't allow one to update any rows in a view, but you have to do the updates in the separate tables.
As MySQL Server is mostly used in applications and on web systems where the application writer has full control on the database usage, most of our users haven't regarded views to be very important. (At least no one has been interested enough in this to be prepared to finance the implementation of views.)
One doesn't need views in MySQL Server to restrict access to columns, as MySQL Server has a very sophisticated privilege system. See section 4.2 General Security Issues and the MySQL Access Privilege System.
Some other SQL databases use `--' to start comments.
MySQL Server has `#' as the start comment character. You can also use
the C comment style /* this is a comment */ with MySQL Server.
See section 6.1.6 Comment Syntax.
MySQL Server Version 3.23.3 and above support the `--' comment style,
provided the comment is followed by a space. This is because this
comment style has caused many problems with automatically generated
SQL queries that have used something like the following code, where
we automatically insert the value of the payment for
!payment!:
UPDATE tbl_name SET credit=credit-!payment!
Think about what happens if the value of payment is negative.
Because 1--1 is legal in SQL, the consequences of allowing
comments to start with `--' are terrible.
Using our implementation of this method of commenting in MySQL Server
Version 3.23.3 and up, 1-- This is a comment is actually safe.
Another safe feature is that the mysql command-line client
removes all lines that start with `--'.
The following information is relevant only if you are running a MySQL version earlier than 3.23.3:
If you have a SQL program in a text file that contains `--' comments you should use:
shell> replace " --" " #" < text-file-with-funny-comments.sql \
| mysql database
instead of the usual:
shell> mysql database < text-file-with-funny-comments.sql
You can also edit the command file ``in place'' to change the `--' comments to `#' comments:
shell> replace " --" " #" -- text-file-with-funny-comments.sql
Change them back with this command:
shell> replace " #" " --" -- text-file-with-funny-comments.sql
The following known errors/bugs are not fixed in MySQL 3.23 because fixing them would involves changing a lot of code which could introduce other even worse bugs. The bugs are also classified as 'not fatal' or 'bearable'.
LOCK TABLE on multiple tables
and then in the same connection doing a DROP TABLE on one of
them while another thread is trying to lock the table. One can however
do a KILL on any of the involved threads to resolve this.
Fixed in 4.0.12.
SELECT MAX(key_column) FROM t1,t2,t3... where one of the tables are
empty doesn't return NULL but instead the maximum value for the
column. Fixed in 4.0.11.
The following problems are known and have a high priority to get fixed:
ANALYZE TABLE on a BDB table may in some case make the table
unusable until one has restarted mysqld. When this happens you will
see errors like the following in the MySQL error file:
001207 22:07:56 bdb: log_flush: LSN past current end-of-log
ALTER TABLE on a BDB table on which you are
running multi-statement transactions until all those transactions complete.
(The transaction will probably be ignored.)
ANALYZE TABLE, OPTIMIZE TABLE, and REPAIR TABLE may
cause problems on tables for which you are using INSERT DELAYED.
LOCK TABLE ... and FLUSH TABLES ... doesn't
guarantee that there isn't a half-finished transaction in progress on the
table.
mysql client on the
database if you are not using the -A option or if you are using
rehash. This is especially notable when you have a big table
cache.
The following problems are known and will be fixed in due time:
RPAD function, or any other string function that ends
up adding blanks to the right, in a query that has to use temporary
table to be resolved, then all resulting strings will be RTRIM'ed. This
is an example of the query:
SELECT RPAD(t1.field1, 50, ' ') AS f2, RPAD(t2.field2, 50, '
') AS f1 FROM table1 as t1 LEFT JOIN table2 AS t2 ON
t1.record=t2.joinID ORDER BY t2.record;
Final result of this bug is that use will not be able to get blanks on
the right side of the resulting field.
The above behaviour exists in all versions of MySQL.
The reason for this is due to the fact that HEAP tables, which are used
first for temporary tables, are not capable of handling VARCHAR columns.
This behaviour will be fixed in one of 4.1 releases.
SET CHARACTER SET, one can't use translated
characters in database, table, and column names.
_ or % with ESCAPE in LIKE
... ESCAPE.
DECIMAL column with a number stored in different
formats (+01.00, 1.00, 01.00), GROUP BY may regard each value
as a different value.
DELETE FROM merge_table used without a WHERE
will only clear the mapping for the table, not delete everything in the
mapped tables.
BLOB values can't ``reliably'' be used in GROUP BY or
ORDER BY or DISTINCT. Only the first max_sort_length
bytes (default 1024) are used when comparing BLOBs in these cases.
This can be changed with the -O max_sort_length option to
mysqld. A workaround for most cases is to use a substring:
SELECT DISTINCT LEFT(blob,2048) FROM tbl_name.
BIGINT or DOUBLE (both are
normally 64 bits long). It depends on the function which precision one
gets. The general rule is that bit functions are done with BIGINT
precision, IF, and ELT() with BIGINT or DOUBLE
precision and the rest with DOUBLE precision. One should try to
avoid using unsigned long long values if they resolve to be bigger than
63 bits (9223372036854775807) for anything else than bit fields!
MySQL Server 4.0 has better BIGINT handling than 3.23.
BLOB and TEXT columns, automatically
have all trailing spaces removed when retrieved. For CHAR types this
is okay, and may be regarded as a feature according to ANSI SQL92. The bug is
that in MySQL Server, VARCHAR columns are treated the same way.
ENUM and SET columns in one table.
MIN(), MAX() and other aggregate functions, MySQL
currently compares ENUM and SET columns by their string
value rather than by the string's relative position in the set.
safe_mysqld redirects all messages from mysqld to the
mysqld log. One problem with this is that if you execute
mysqladmin refresh to close and reopen the log,
stdout and stderr are still redirected to the old log.
If you use --log extensively, you should edit safe_mysqld to
log to `'hostname'.err' instead of `'hostname'.log' so you can
easily reclaim the space for the old log by deleting the old one and
executing mysqladmin refresh.
UPDATE statement, columns are updated from left to right. If
you refer to an updated column, you will get the updated value instead of the
original value. For example:
mysql> UPDATE tbl_name SET KEY=KEY+1,KEY=KEY+1;This will update
KEY with 2 instead of with 1.
mysql> SELECT * FROM temporary_table, temporary_table AS t2;
RENAME doesn't work with TEMPORARY tables or tables used in a
MERGE table.
DISTINCT differently if you are using
'hidden' columns in a join or not. In a join, hidden columns are
counted as part of the result (even if they are not shown) while in
normal queries hidden columns don't participate in the DISTINCT
comparison. We will probably change this in the future to never compare
the hidden columns when executing DISTINCT.
An example of this is:
SELECT DISTINCT mp3id FROM band_downloads
WHERE userid = 9 ORDER BY id DESC;
and
SELECT DISTINCT band_downloads.mp3id
FROM band_downloads,band_mp3
WHERE band_downloads.userid = 9
AND band_mp3.id = band_downloads.mp3id
ORDER BY band_downloads.id DESC;
In the second case you may in MySQL Server 3.23.x get two identical rows
in the result set (because the hidden id column may differ).
Note that this happens only for queries where you don't have the
ORDER BY columns in the result, something that you are not allowed
to do in ANSI SQL.
rollback data, some things
behave a little differently in MySQL Server than in other SQL servers.
This is just to ensure that MySQL Server never needs to do a rollback
for a SQL command. This may be a little awkward at times as column
values must be checked in the application, but this will actually give
you a nice speed increase as it allows MySQL Server to do some
optimisations that otherwise would be very hard to do.
If you set a column to an incorrect value, MySQL Server will, instead of
doing a rollback, store the best possible value in the column:
NULL into a column that doesn't take
NULL values, MySQL Server will store 0 or '' (empty
string) in it instead. (This behaviour can, however, be changed with the
-DDONT_USE_DEFAULT_FIELDS compile option.)
DATE and
DATETIME columns (like 2000-02-31 or 2000-02-00). The idea is
that it's not the SQL server job to validate date. If MySQL can store a
date and retrieve exactly the same date, then MySQL will store the
date. If the date is totally wrong (outside the server's ability to store
it), then the special date value 0000-00-00 will be stored in the column.
ENUM column to an unsupported value, it will be set to
the error value empty string, with numeric value 0.
SET column to an unsupported value, the value will
be ignored.
PROCEDURE on a query that returns an empty set,
in some cases the PROCEDURE will not transform the columns.
MERGE doesn't check if the underlying
tables are of compatible types.
NaN, -Inf, and Inf
values in double. Using these will cause problems when trying to export
and import data. We should as an intermediate solution change NaN to
NULL (if possible) and -Inf and Inf to the
minimum respective maximum possible double value.
LIMIT on negative numbers are treated as big positive numbers.
ALTER TABLE to first add a UNIQUE index to a
table used in a MERGE table and then use ALTER TABLE to
add a normal index on the MERGE table, the key order will be
different for the tables if there was an old key that was not unique in the
table. This is because ALTER TABLE puts UNIQUE keys before
normal keys to be able to detect duplicate keys as early as possible.
The following are known bugs in earlier versions of MySQL:
DROP TABLE on a table that is
one among many tables that is locked with LOCK TABLES.
LOCK table with WRITE.
FLUSH TABLES.
UPDATE that updated a key with
a WHERE on the same key may have failed because the key was used to
search for records and the same row may have been found multiple times:
UPDATE tbl_name SET KEY=KEY+1 WHERE KEY > 100;A workaround is to use:
mysql> UPDATE tbl_name SET KEY=KEY+1 WHERE KEY+0 > 100;This will work because MySQL Server will not use an index on expressions in the
WHERE clause.
For platform-specific bugs, see the sections about compiling and porting.
This section lists the features that we plan to implement in MySQL Server.
Everything in this list is approximately in the order it will be done. If you want to affect the priority order, please register a license or support us and tell us what you want to have done more quickly. See section 1.4 MySQL Support and Licensing.
The plan is that we in the future will support the full ANSI SQL99 standard, but with a lot of useful extensions. The challenge is to do this without sacrificing the speed or compromising the code.
All done. We now only do bug fixes for MySQL 4.0. See section D.3 Changes in release 4.0.x (Gamma). Development has shifted to 4.1 & 5.0
The following features are planned for inclusion into MySQL 4.1. For a list what is already done in MySQL 4.1, see See section D.2 Changes in release 4.1.x (Alpha).
The following features are planned for inclusion into MySQL 5.0. Note that because we have many developers that are working on different projects, there will also be many additional features. There is also a small chance that some of these features will be added to MySQL 4.1. For a list what is already done in MySQL 4.1, see See section D.2 Changes in release 4.1.x (Alpha).
SHOW COLUMNS FROM table_name (used by mysql client to allow
expansions of column names) should not open the table, only the
definition file. This will require less memory and be much faster.
ROLLUP and CUBE OLAP (Online Analytical Processing) grouping
options for data warehousing applications.
DELETE on MyISAM tables to use the record cache.
To do this, we need to update the threads record cache when we update
the `.MYD' file.
SET CHARACTER SET we should translate the whole query
at once and not only strings. This will enable users to use the translated
characters in database, table, and column names.
RENAME TABLE on a table used in an active
MERGE table possibly corrupting the table.
RENAME DATABASE. To make this safe for all storage engines,
it should work as follows:
RENAME command.
VARCHAR support (there is already support for this in
MyISAM).
BIT type to take 1 bit (now BIT takes 1 char).
HEAP) tables:
INSERT ... SELECT to optionally use concurrent inserts.
SELECT MIN(column)
... GROUP BY.
long_query_time with a granularity
in microseconds.
myisampack code into the server.
INSERT/DELETE/UPDATE so that we
can gracefully recover if the index file gets full.
ALTER TABLE on a table that is symlinked to another
disk, create temporary tables on this disk.
DATE/DATETIME type that handles time zone information
properly so that dealing with dates in different time zones is easier.
MyISAM)
without threads.
INSERT SQL_CONCURRENT and mysqld --concurrent-insert to do
a concurrent insert at the end of the file if the file is read-locked.
lockd works with modern Linux kernels; if not, we have
to fix lockd! To test this, start mysqld with
--enable-locking and run the different fork* test suits. They shouldn't
give any errors if lockd works.
LIMIT, like in LIMIT @a,@b.
UPDATE statements. For example:
UPDATE TABLE foo SET @a=a+b,a=@a, b=@a+c.
GROUP BY, as in the following example:
SELECT id, @a:=COUNT(*), SUM(sum_col)/@a FROM table_name GROUP BY id.
DEFAULT values to columns. Give an error when using
an INSERT that doesn't contain a column that doesn't have a
DEFAULT.
mysql_query() commands in a row
without reading results or give a nice error message when one does this.
ctime() doesn't work on some FreeBSD systems.
IMAGE option to LOAD DATA INFILE to not update
TIMESTAMP and AUTO_INCREMENT fields.
LOAD DATE INFILE ... UPDATE syntax.
LOAD DATA INFILE ... REPLACE INTO now.
LOAD DATA INFILE understand syntax like:
LOAD DATA INFILE 'file_name.txt' INTO TABLE tbl_name
TEXT_FIELDS (text_field1, text_field2, text_field3)
SET table_field1=CONCAT(text_field1, text_field2),
table_field3=23
IGNORE text_field3
This can be used to skip over extra columns in the text file,
or update columns based on expressions of the read data.
LOAD DATA INFILE 'file_name' INTO TABLE 'table_name' ERRORS TO err_table_name.
This would cause any errors and warnings to be logged into the
err_table_name table. That table would have a structure like:
line_number - line number in datafile error_message - the error/warning message and maybe data_line - the line from the datafile
mysql to Netscape.
LOCK DATABASES (with various options.)
t1 JOIN t2 ON ... and t1 JOIN t2 USING ...
Currently, you can only use this syntax with LEFT JOIN.
show status. Records reads and
updates. Selects on 1 table and selects with joins. Mean number of
tables in select. Number of ORDER BY and GROUP BY queries.
mysql in the middle of a query, you should open
another connection and kill the old running query.
Alternatively, an attempt should be made to detect this in the server.
SHOW INFO FROM tbl_name for basic table information
should be implemented.
SELECT a FROM crash_me LEFT JOIN crash_me2 USING (a); in this
case a is assumed to come from the crash_me table.
CONNECT BY PRIOR ... to search hierarchy structures.
mysqladmin copy database new-database; requires COPY
command to be added to mysqld.
SHOW HOSTS for printing information about the hostname cache.
DELETE and REPLACE options to the UPDATE statement
(this will delete rows when one gets a duplicate key error while updating).
DATETIME to store fractions of seconds.
NULL for calculated columns.
Item_copy_string on numerical values to avoid
number->string->number conversion in case of:
SELECT COUNT(*)*(id+0) FROM table_name GROUP BY id
ALTER TABLE doesn't abort clients
that execute INSERT DELAYED.
UPDATE clause,
they contain the old values from before the update started.
pread()/pwrite() on Windows to enable
concurrent inserts.
SUM(DISTINCT).
ANY(), EVERY(), and SOME() group functions. In
ANSI SQL these work only on boolean columns, but we can extend these to
work on any columns/expressions by applying: value == 0 -> FALSE and
value <> 0 -> TRUE.
MAX(column) is the same as the column type:
mysql> CREATE TABLE t1 (a DATE); mysql> INSERT INTO t1 VALUES (NOW()); mysql> CREATE TABLE t2 SELECT MAX(a) FROM t1; mysql> SHOW COLUMNS FROM t2;
UPDATE the row
if it exists and INSERT a new row if the row didn't exist
(like REPLACE works with INSERT / DELETE).
get_changed_tables(timeout,table1,table2,...).
SET TIMESTAMP=#;.
MyISAM tables, probably after
the implementation of stored procedures with triggers.
MINUS, INTERSECT, and FULL OUTER JOIN.
(Currently UNION [in 4.0] and LEFT OUTER JOIN are supported.)
SQL_OPTION MAX_SELECT_TIME=# to put a time limit on a query.
LIMIT to allow retrieval of data from the end of a result set.
safe_mysqld: according to FSSTND (which
Debian tries to follow) PID files should go into `/var/run/<progname>.pid'
and log files into `/var/log'. It would be nice if you could put the
"DATADIR" in the first declaration of "pidfile" and "log", so the
placement of these files can be changed with a single statement.
zlib() for gzip-ed files to LOAD DATA INFILE.
BLOB columns (partly solved now).
AUTO_INCREMENT value when one sets a column to 0.
Use NULL instead.
JOIN with parentheses.
GET_LOCK. When doing this,
one must also handle the possible deadlocks this change will introduce.
Time is given according to amount of work, not real time.
Our users have successfully run their own benchmarks against a number
of Open Source and traditional database servers.
We are aware of tests against Oracle server, DB/2 server,
Microsoft SQL Server, and other commercial products.
Due to legal reasons we are restricted from publishing some of those
benchmarks in our reference manual.
This section includes a comparison with mSQL for historical
reasons and with PostgreSQL as it is also an Open Source
database. If you have benchmark results that we can publish, please
contact us at benchmarks@mysql.com.
For comparative lists of all supported functions and types as well
as measured operational limits of many different database systems,
see the crash-me web page at
http://www.mysql.com/information/crash-me.php.
mSQLmSQL should be quicker at:
INSERT operations into very simple tables with few columns and keys.
CREATE TABLE and DROP TABLE.
SELECT on something that isn't an index. (A table scan is very
easy.)
mSQL (and
most other SQL implementations) on the following:
SELECT operations.
VARCHAR columns.
SELECT with many expressions.
SELECT on large tables.
mSQL, once one
connection is established, all others must wait until the first has
finished, regardless of whether the connection is running a query
that is short or long. When the first connection terminates, the
next can be served, while all the others wait again, etc.
mSQL can become pathologically slow if you change the order of
tables in a SELECT. In the benchmark suite, a time more than
15,000 times slower than MySQL Server was seen. This is due to mSQL's
lack of a join optimiser to order tables in the optimal order.
However, if you put the tables in exactly the right order in
mSQL2 and the WHERE is simple and uses index columns,
the join will be relatively fast!
See section 5.1.4 The MySQL Benchmark Suite.
ORDER BY and GROUP BY.
DISTINCT.
TEXT or BLOB columns.
GROUP BY and HAVING.
mSQL does not support GROUP BY at all.
MySQL Server supports a full GROUP BY with both HAVING and
the following functions: COUNT(), AVG(), MIN(),
MAX(), SUM(), and STD(). COUNT(*) is
optimised to return very quickly if the SELECT retrieves from
one table, no other columns are retrieved, and there is no
WHERE clause. MIN() and MAX() may take string
arguments.
INSERT and UPDATE with calculations.
MySQL Server can do calculations in an INSERT or UPDATE.
For example:
mysql> UPDATE SET x=x*10+y WHERE x<20;
SELECT with functions.
MySQL Server has many functions (too many to list here; see section 6.3 Functions for Use in SELECT and WHERE Clauses).
MEDIUMINT that is 3 bytes long. If you have 100 million
records, saving even 1 byte per record is very important.
mSQL2 has a more limited set of column types, so it is
more difficult to get small tables.
mSQL stability, so we cannot say
anything about that.
mSQL, and is also less expensive
than mSQL. Whichever product you choose to use, remember to
at least consider paying for a license or e-mail support.
mSQL with
some added features.
mSQL has a JDBC driver, but we have too little
experience with it to compare.
GROUP BY, and so on are still not implemented in mSQL, it
has a lot of catching up to do. To get some perspective on this, you
can view the mSQL `HISTORY' file for the last year and
compare it with the News section of the MySQL Reference Manual
(see section D MySQL Change History). It should be pretty obvious which one has developed
most rapidly.
mSQL and MySQL Server have many interesting third-party
tools. Because it is very easy to port upward (from mSQL to
MySQL Server), almost all the interesting applications that are available for
mSQL are also available for MySQL Server.
MySQL Server comes with a simple msql2mysql program that fixes
differences in spelling between mSQL and MySQL Server for the
most-used C API functions.
For example, it changes instances of msqlConnect() to
mysql_connect(). Converting a client program from mSQL to
MySQL Server usually requires only minor effort.
mSQL Tools for MySQL
According to our experience, it doesn't take long to convert tools
such as msql-tcl and msqljava that use the
mSQL C API so that they work with the MySQL C API.
The conversion procedure is:
msql2mysql on the source. This requires
the replace program, which is distributed with MySQL Server.
Differences between the mSQL C API and the MySQL C API are:
MYSQL structure as a connection type (mSQL
uses an int).
mysql_connect() takes a pointer to a MYSQL structure as a
parameter. It is easy to define one globally or to use malloc()
to get one. mysql_connect() also takes two parameters for
specifying the user and password. You may set these to
NULL, NULL for default use.
mysql_error() takes the MYSQL structure as a parameter.
Just add the parameter to your old msql_error() code if you are
porting old code.
mSQL returns only a text error message.
mSQL and MySQL Client/Server Communications Protocols DifferThere are enough differences that it is impossible (or at least not easy) to support both.
The most significant ways in which the MySQL protocol differs
from the mSQL protocol are listed here:
mSQL 2.0 SQL Syntax Differs from MySQLColumn types
MySQL Server
CREATE TABLE Syntax):
ENUM type for one of a set of strings.
SET type for many of a set of strings.
BIGINT type for 64-bit integers.
UNSIGNED option for integer and floating-point columns.
ZEROFILL option for integer columns.
AUTO_INCREMENT option for integer columns that are a
PRIMARY KEY.
See section 8.4.3.130 mysql_insert_id().
DEFAULT value for all columns.
mSQL2
mSQL column types correspond to the MySQL types shown in the following table:
mSQL type | Corresponding MySQL type |
CHAR(len) | CHAR(len)
|
TEXT(len) | TEXT(len). len is the maximal length.
And LIKE works.
|
INT | INT. With many more options!
|
REAL | REAL. Or FLOAT. Both 4- and 8-byte versions are available.
|
UINT | INT UNSIGNED
|
DATE | DATE. Uses ANSI SQL format rather than mSQL's own format.
|
TIME | TIME
|
MONEY | DECIMAL(12,2). A fixed-point value with two decimals.
|
Index Creation
MySQL Server
CREATE TABLE
statement.
mSQL
CREATE INDEX statements.
To Insert a Unique Identifier into a Table
MySQL Server
AUTO_INCREMENT as a column type
specifier.
See section 8.4.3.130 mysql_insert_id().
mSQL
SEQUENCE on a table and select the _seq column.
To Obtain a Unique Identifier for a Row
MySQL Server
PRIMARY KEY or UNIQUE key to the table and use this.
New in Version 3.23.11: If the PRIMARY or UNIQUE key consists of only one
column and this is of type integer, one can also refer to it as
_rowid.
mSQL
_rowid column. Observe that _rowid may change over time
depending on many factors.
To Get the Time a Column Was Last Modified
MySQL Server
TIMESTAMP column to the table. This column is automatically set
to the current date and time for INSERT or UPDATE statements if
you don't give the column a value or if you give it a NULL value.
mSQL
_timestamp column.
NULL Value Comparisons
MySQL Server
NULL is always NULL.
mSQL
mSQL, NULL = NULL is TRUE. You
must change =NULL to IS NULL and <>NULL to
IS NOT NULL when porting old code from mSQL to MySQL Server.
String Comparisons
MySQL Server
BINARY attribute, which causes comparisons to be done according to the
ASCII order used on the MySQL server host.
mSQL
Case-insensitive Searching
MySQL Server
LIKE is a case-insensitive or case-sensitive operator, depending on
the columns involved. If possible, MySQL uses indexes if the
LIKE argument doesn't start with a wildcard character.
mSQL
CLIKE.
Handling of Trailing Spaces
MySQL Server
CHAR and VARCHAR
columns. Use a TEXT column if this behaviour is not desired.
mSQL
WHERE Clauses
MySQL Server
AND is evaluated
before OR). To get mSQL behaviour in MySQL Server, use
parentheses (as shown in an example later in this section).
mSQL
mSQL query:
mysql> SELECT * FROM table WHERE a=1 AND b=2 OR a=3 AND b=4;To make MySQL Server evaluate this the way that
mSQL would,
you must add parentheses:
mysql> SELECT * FROM table WHERE (a=1 AND (b=2 OR (a=3 AND (b=4))));
Access Control
MySQL Server
mSQL
PostgreSQLWhen reading the following, please note that both products are continually evolving. We at MySQL AB and the PostgreSQL developers are both working on making our respective databases as good as possible, so we are both a serious alternative to any commercial database.
The following comparison is made by us at MySQL AB. We have tried to be as accurate and fair as possible, but although we know MySQL Server thoroughly, we don't have a full knowledge of all PostgreSQL features, so we may have got some things wrong. We will, however, correct these when they come to our attention.
We would first like to note that PostgreSQL and MySQL Server are both widely used
products, but with different design goals, even if we are both striving
toward ANSI SQL compliancy. This means that for some applications MySQL Server
is more suited, while for others PostgreSQL is more suited. When choosing
which database to use, you should first check if the database's feature set
satisfies your application. If you need raw speed, MySQL Server is probably your
best choice. If you need some of the extra features that only PostgreSQL
can offer, you should use PostgreSQL.
When adding things to MySQL Server we take pride to do an optimal, definite solution. The code should be so good that we shouldn't have any need to change it in the foreseeable future. We also do not like to sacrifice speed for features but instead will do our utmost to find a solution that will give maximal throughput. This means that development will take a little longer, but the end result will be well worth this. This kind of development is only possible because all server code are checked by one of a few (currently two) persons before it's included in the MySQL server.
We at MySQL AB believe in frequent releases to be able to push out new features quickly to our users. Because of this we do a new small release about every three weeks, and a major branch every year. All releases are thoroughly tested with our testing tools on a lot of different platforms.
PostgreSQL is based on a kernel with lots of contributors. In this setup it makes sense to prioritise adding a lot of new features, instead of implementing them optimally, because one can always optimise things later if there arises a need for this.
Another big difference between MySQL Server and PostgreSQL is that nearly all of the code in the MySQL server is coded by developers that are employed by MySQL AB and are still working on the server code. The exceptions are the transaction engines and the regexp library.
This is in sharp contrast to the PostgreSQL code, the majority of which is coded by a big group of people with different backgrounds. It was only recently that the PostgreSQL developers announced that their current developer group had finally had time to take a look at all the code in the current PostgreSQL release.
Both of the aforementioned development methods have their own merits and drawbacks. We here at MySQL AB think, of course, that our model is better because our model gives better code consistency, more optimal and reusable code, and in our opinion, fewer bugs. Because we are the authors of the MySQL server code, we are better able to coordinate new features and releases.
On the crash-me page
(http://www.mysql.com/information/crash-me.php)
you can find a list of those database constructs and limits that
one can detect automatically with a program. Note, however, that a lot of
the numerical limits may be changed with startup options for their respective
databases. This web page is, however, extremely useful when you want to
ensure that your applications work with many different databases or
when you want to convert your application from one database to another.
MySQL Server offers the following advantages over PostgreSQL:
MySQL Server is generally much faster than PostgreSQL. MySQL
4.0.1 also has a query cache that can boost up the query speed for
mostly-read-only sites many times.
Cygwin emulation. We have
heard that PostgreSQL is not yet that stable on Windows but we haven't
been able to verify this ourselves.
VACUUM
once in a while to reclaim space from UPDATE and DELETE
commands and to perform statistics analyses that are critical to get
good performance with PostgreSQL. VACUUM is also needed after
adding a lot of new rows to a table. On a busy system with lots of changes,
VACUUM must be run very frequently, in the worst cases even
many times a day. During the VACUUM run, which may take hours
if the database is big, the database is, from a production standpoint,
practically dead. Please note: in PostgreSQL version 7.2, basic vacuuming
no longer locks tables, thus allowing normal user access during the vacuum.
A new VACUUM FULL command does old-style vacuum by locking the table
and shrinking the on-disk copy of the table.
crash-me
(http://www.mysql.com/information/crash-me.php), as well
as a benchmark suite. The test system is actively updated with code to
test each new feature and almost all reproduceable bugs that have come to
our attention. We test MySQL Server with these on a lot of platforms before
every release. These tests are more sophisticated than anything we have
seen from PostgreSQL, and they ensure that the MySQL Server is kept to a high
standard.
PostgreSQL.
ALTER TABLE.
HEAP
tables or disk based MyISAM. See section 7 MySQL Table Types.
InnoDB, and BerkeleyDB. Because every
transaction engine performs differently under different conditions, this
gives the application writer more options to find an optimal solution for
his or her setup, if need be per individual table. See section 7 MySQL Table Types.
MERGE tables gives you a unique way to instantly make a view over
a set of identical tables and use these as one. This is perfect for
systems where you have log files that you order, for example, by month.
See section 7.2 MERGE Tables.
myisampack, The MySQL Compressed Read-only Table Generator.
INSERT,
SELECT, and UPDATE/DELETE grants per user on a database or
a table, MySQL Server allows you to define a full set of different
privileges on the database, table, and column level. MySQL Server also
allows you to specify the privilege on host and user combinations.
See section 4.3.1 GRANT and REVOKE Syntax.
InnoDB) are implemented as files
(one table per file), which makes it really easy to back up, move, delete,
and even symlink databases and tables, even when the server is down.
MyISAM tables (the most common
MySQL table type). A repair tool is only needed when a physical corruption
of a datafile happens, usually from a hardware failure. It allows a
majority of the data to be recovered.
Drawbacks with MySQL Server compared to PostgreSQL:
MyISAM tables, is
in many cases faster than page locks, row locks, or versioning. The
drawback, however, is that if one doesn't take into account how table
locks work, a single long-running query can block a table for updates
for a long time. This can usually be avoided when designing the
application. If not, one can always switch the trouble table to use one
of the transactional table types. See section 5.3.2 Table Locking Issues.
UPDATE and in MySQL Server 4.1 with subqueries.
In MySQL Server 4.0 one can use multi-table deletes to delete from many
tables at the same time. See section 6.4.6 DELETE Syntax.
PostgreSQL currently offers the following advantages over MySQL Server:
Note that because we know the MySQL road map, we have included in the following table the version when MySQL Server should support this feature. Unfortunately we couldn't do this for previous comparisons, because we don't know the PostgreSQL roadmap.
| Feature | MySQL version |
| Subqueries | 4.1 |
| Foreign keys | 5.0 (3.23 with InnoDB) |
| Views | 5.0 |
| Stored procedures | 5.0 |
| Triggers | 5.0 |
| Unions | 4.0 |
| Full join | 4.1 |
| Constraints | 4.1 or 5.0 |
| Cursors | 4.1 or 5.0 |
| R-trees | 4.1 (for MyISAM tables) |
| Inherited tables | Not planned |
| Extensible type system | Not planned |
Other reasons someone may consider using PostgreSQL:
Drawbacks with PostgreSQL compared to MySQL Server:
VACUUM makes PostgreSQL hard to use in a 24/7 environment.
INSERT, DELETE, and UPDATE.
For a complete list of drawbacks, you should also examine the first table in this section.
The only Open Source benchmark that we know of that can be used to
benchmark MySQL Server and PostgreSQL (and other databases) is our own. It can
be found at http://www.mysql.com/information/benchmarks.html.
We have many times asked the PostgreSQL developers and some PostgreSQL users to help us extend this benchmark to make it the definitive benchmark for databases, but unfortunately we haven't gotten any feedback for this.
We, the MySQL developers, have, because of this, spent a lot of hours to get maximum performance from PostgreSQL for the benchmarks, but because we don't know PostgreSQL intimately, we are sure that there are things that we have missed. We have on the benchmark page documented exactly how we did run the benchmark so that it should be easy for anyone to repeat and verify our results.
The benchmarks are usually run with and without the --fast option.
When run with --fast we are trying to use every trick the server can
do to get the code to execute as fast as possible. The idea is that the
normal run should show how the server would work in a default setup and
the --fast run shows how the server would do if the application
developer would use extensions in the server to make his application run
faster.
When running with PostgreSQL and --fast we do a VACUUM
after every major table UPDATE and DROP TABLE to make the
database in perfect shape for the following SELECTs. The time for
VACUUM is measured separately.
When running with PostgreSQL 7.1.1 we could, however, not run with
--fast because during the INSERT test, the postmaster (the
PostgreSQL daemon) died and the database was so corrupted that it was
impossible to restart postmaster. After this happened twice, we decided
to postpone the --fast test until the next PostgreSQL release. The
details about the machine we run the benchmark on can be found on the
benchmark page.
Before going to the other benchmarks we know of, we would like to give some background on benchmarks.
It's very easy to write a test that shows any database to be the best database in the world, by just restricting the test to something the database is very good at and not testing anything that the database is not good at. If one, after doing this, summarises the result as a single figure, things are even easier.
This would be like us measuring the speed of MySQL Server compared to PostgreSQL by looking at the summary time of the MySQL benchmarks on our web page. Based on this MySQL Server would be more than 40 times faster than PostgreSQL, something that is, of course, not true. We could make things even worse by just taking the test where PostgreSQL performs worst and claim that MySQL Server is more than 2000 times faster than PostgreSQL.
The case is that MySQL does a lot of optimisations that PostgreSQL doesn't do. This is, of course, also true the other way around. An SQL optimiser is a very complex thing, and a company could spend years just making the optimiser faster and faster.
When looking at the benchmark results you should look for things that you do in your application and just use these results to decide which database would be best suited for your application. The benchmark results also show things a particular database is not good at and should give you a notion about things to avoid and what you may have to do in other ways.
We know of two benchmark tests that claim that PostgreSQL performs better than MySQL Server. These both where multi-user tests, a test that we here at MySQL AB haven't had time to write and include in the benchmark suite, mainly because it's a big task to do this in a manner that is fair to all databases.
One is the benchmark paid for by Great Bridge, the company that for 16 months attempted to build a business based on PostgreSQL but now has ceased operations. This is probably the worst benchmark we have ever seen anyone conduct. This was not only tuned to only test what PostgreSQL is absolutely best at, but it was also totally unfair to every other database involved in the test.
Note: We know that even some of the main PostgreSQL developers did not like the way Great Bridge conducted the benchmark, so we don't blame the PostgreSQL team for the way the benchmark was done.
This benchmark has been condemned in a lot of postings and newsgroups, so here we will just briefly repeat some things that were wrong with it.
Open Source company like us to verify the benchmarks,
or even check how the benchmarks were really done. The tool is not even
a true benchmark tool, but an application/setup testing tool. To refer
to this as a ``standard'' benchmark tool is to stretch the truth a long way.
VACUUM before the test) and tuned the startup for the tests,
something they hadn't done for any of the other databases involved. They
say ``This process optimises indexes and frees up disk space a bit. The
optimised indexes boost performance by some margin.'' Our benchmarks
clearly indicate that the difference in running a lot of selects on a
database with and without VACUUM can easily differ by a factor
of 10.
SELECTs and JOINs (especially
after a VACUUM), but doesn't perform as well on INSERTs or
UPDATEs. The benchmarks seem to indicate that only SELECTs
were done (or very few updates). This could easily explain the good results
for PostgreSQL in this test. The bad results for MySQL will be obvious a
bit down in this document.
Tim Perdue, a long-time PostgreSQL fan and a reluctant MySQL user, published a comparison on PHPbuilder (http://www.phpbuilder.com/columns/tim20001112.php3).
When we became aware of the comparison, we phoned Tim Perdue about this because there were a lot of strange things in his results. For example, he claimed that MySQL Server had a problem with five users in his tests, when we know that there are users with similar machines as his that are using MySQL Server with 2000 simultaneous connections doing 400 queries per second. (In this case the limit was the web bandwidth, not the database.)
It sounded like he was using a Linux kernel that either had some problems with many threads, such as kernels before 2.4, which had a problem with many threads on multi-CPU machines. We have documented in this manual how to fix this and Tim should be aware of this problem.
The other possible problem could have been an old glibc library and that Tim didn't use a MySQL binary from our site, which is linked with a corrected glibc library, but had compiled a version of his own. In any of these cases, the symptom would have been exactly what Tim had measured.
We asked Tim if we could get access to his data so that we could repeat the benchmark and if he could check the MySQL version on the machine to find out what was wrong and he promised to come back to us about this. He has not done that yet.
Because of this we can't put any trust in this benchmark either. :(
Over time things also change and the preceding benchmarks are not that relevant anymore. MySQL Server now has a couple of different storage engines with different speed/concurrency tradeoffs. See section 7 MySQL Table Types. It would be interesting to see how the above tests would run with the different transactional table types in MySQL Server. PostgreSQL has, of course, also got new features since the test was made. As these tests are not publicly available there is no way for us to know how the database would perform in the same tests today.
Conclusion:
The only benchmarks that exist today that anyone can download and run
against MySQL Server and PostgreSQL are the MySQL benchmarks.
We here at MySQL AB
believe that Open Source databases should be tested with Open Source tools!
This is the only way to ensure that no one does tests that nobody can
reproduce and use this to claim that one database is better than another.
Without knowing all the facts it's impossible to answer the claims of the
tester.
The thing we find strange is that every test we have seen about PostgreSQL, that is impossible to reproduce, claims that PostgreSQL is better in most cases while our tests, which anyone can reproduce, clearly show otherwise. With this we don't want to say that PostgreSQL isn't good at many things (it is!) or that it isn't faster than MySQL Server under certain conditions. We would just like to see a fair test where PostgreSQL performs very well, so that we could get some friendly competition going!
For more information about our benchmark suite, see section 5.1.4 The MySQL Benchmark Suite.
We are working on an even better benchmark suite, including multi-user tests, and a better documentation of what the individual tests really do and how to add more tests to the suite.
This chapter describes how to obtain and install MySQL:
The recommended way to install MySQL on Linux is by using the RPM
packages. The MySQL RPMs are currently being built on a SuSE Linux 7.3
system but should work on most versions of Linux that support rpm
and use glibc.
If you have problems with an RPM file, for example, if you receive the error
``Sorry, the host 'xxxx' could not be looked up''@-see
section 2.6.1.1 Linux Notes for Binary Distributions.
The RPM files you may want to use are:
MySQL-server-VERSION.i386.rpm
The MySQL server. You will need this unless you only want to
connect to a MySQL server running on another machine. Please note
that this package was called MySQL-VERSION.i386.rpm before
MySQL 4.0.10.
MySQL-client-VERSION.i386.rpm
The standard MySQL client programs. You probably always want to
install this package.
MySQL-bench-VERSION.i386.rpm
Tests and benchmarks. Requires Perl and msql-mysql-modules RPMs.
MySQL-devel-VERSION.i386.rpm
Libraries and include files needed if you want to compile other
MySQL clients, such as the Perl modules.
MySQL-shared-VERSION.i386.rpm
This package contains the shared libraries (libmysqlclient.so*)
which certain languages and applications need to dynamically load and
use MySQL.
MySQL-embedded-VERSION.i386.rpm
The embedded MySQL server library (MySQL 4.x and onwards only).
MySQL-VERSION.src.rpm
This contains the source code for all of the previous packages. It can also
be used to rebuild the RPMs on other architectures (for example, Alpha or SPARC).
To see all files in an RPM package, run:
shell> rpm -qpl MySQL-VERSION.i386.rpm
To perform a standard minimal installation, run:
shell> rpm -i MySQL-server-VERSION.i386.rpm MySQL-client-VERSION.i386.rpm
To install just the client package, run:
shell> rpm -i MySQL-client-VERSION.i386.rpm
The RPM places data in `/var/lib/mysql'. The RPM also creates the appropriate entries in `/etc/init.d/' to start the server automatically at boot time. (This means that if you have performed a previous installation, you may want to make a copy of your previously installed MySQL startup file if you made any changes to it, so you don't lose your changes.)
If you want to install the MySQL RPM on older Linux distributions that do not support init scripts in `/etc/init.d' (directly or via a symlink), you should create a symbolic link pointing to the old location before installing the RPM:
shell> cd /etc ; ln -s rc.d/init.d .
However, all current major Linux distributions should already support this new directory layout as it is required for LSB (Linux Standard Base) compliance.
After installing the RPM file(s), the mysqld daemon should be up and
running and you should now be able to start using MySQL.
See section 2.4 Post-installation Setup and Testing.
If something goes wrong, you can find more information in the binary installation chapter. See section 2.2.10 Installing a MySQL Binary Distribution.
The MySQL server for Windows is available in two distribution types:
Generally speaking, you should use the binary distribution.
You will need the following:
MAX_ROWS and
AVG_ROW_LENGTH when you create the table. See section 6.5.3 CREATE TABLE Syntax.
ZIP program to unpack the distribution file.
ODBC, you
will also need the MyODBC driver. See section 8.3 MySQL ODBC Support.
C:\> NET STOP MySQLOtherwise, use:
C:\mysql\bin> mysqladmin -u root shutdown
C:\mysql\bin> mysqld-max-nt --remove
Browse button to specify your
preferred directory.
Starting with MySQL 3.23.38, the Windows distribution includes both the normal and the MySQL-Max server binaries. Here is a list of the different MySQL servers you can use:
| Binary | Description |
mysqld | Compiled with full debugging and automatic memory allocation checking, symbolic links, InnoDB, and BDB tables. |
mysqld-opt | Optimised binary with no support for transactional tables. |
mysqld-nt | Optimised binary for NT/2000/XP with support for named pipes. You can run this version on Windows 9x/Me, but in this case no named pipes are created and you must have TCP/IP installed. |
mysqld-max | Optimised binary with support for symbolic links, InnoDB and BDB tables. |
mysqld-max-nt |
Like mysqld-max, but compiled with support for named pipes.
|
Starting from 3.23.50, named pipes are only enabled if one starts mysqld with
--enable-named-pipe.
All of the preceding binaries are optimised for the Pentium Pro processor but should work on any Intel processor >= i386.
You will need to use an option file to specify your MySQL configuration under the following circumstances:
Normally you can use the WinMySQLAdmin tool to edit the
option file my.ini. In this case you don't have to worry
about the following section.
There are two option files with the same function: `my.cnf' and
`my.ini'. However, to avoid confusion, it's best if you use only
of one them. Both files are plain text. The `my.cnf' file, if used,
should be created in the root directory of the C drive. The `my.ini'
file, if used, should be created in the Windows system directory. (This
directory is typically something like `C:\WINDOWS' or `C:\WINNT'.
You can determine its exact location from the value of the windir
environment variable.) MySQL looks first for the my.ini file,
then for the `my.cnf' file.
If your PC uses a boot loader where the C drive isn't the boot drive,
your only option is to use the `my.ini' file. Also note that
if you use the WinMySQLAdmin tool, it uses only the `my.ini'
file. The `\mysql\bin' directory contains a help file with
instructions for using this tool.
Using notepad.exe, create the option file and edit the
[mysqld] section to specify values for the basedir and
datadir parameters:
[mysqld] # set basedir to installation path, e.g., c:/mysql basedir=the_install_path # set datadir to location of data directory, # e.g., c:/mysql/data or d:/mydata/data datadir=the_data_path
Note that Windows pathnames should be specified in option files using forward slashes rather than backslashes. If you do use backslashes, you must double them.
If you would like to use a data directory different from the default of `c:\mysql\data', you must copy the entire contents of the `c:\mysql\data' directory to the new location.
If you want to use the InnoDB transactional tables, you
need to manually create two new directories to hold the InnoDB
data and log files@-e.g., `c:\ibdata' and `c:\iblogs'.
You will also need to add some extra lines to the option
file. See section 7.5.2 InnoDB Startup Options.
If you don't want to use InnoDB tables, add the
skip-innodb option to the option file.
Now you are ready to test starting the server.
Testing from a DOS command prompt is the best thing to do because the server displays status messages that appear in the DOS window. If something is wrong with your configuration, these messages will make it easier for you to identify and fix any problems.
Make sure you are in the directory where the server is located, then enter this command:
C:\mysql\bin> mysqld-max --standalone
You should see the following messages as the server starts up:
InnoDB: The first specified datafile c:\ibdata\ibdata1 did not exist: InnoDB: a new database to be created! InnoDB: Setting file c:\ibdata\ibdata1 size to 209715200 InnoDB: Database physically writes the file full: wait... InnoDB: Log file c:\iblogs\ib_logfile0 did not exist: new to be created InnoDB: Setting log file c:\iblogs\ib_logfile0 size to 31457280 InnoDB: Log file c:\iblogs\ib_logfile1 did not exist: new to be created InnoDB: Setting log file c:\iblogs\ib_logfile1 size to 31457280 InnoDB: Log file c:\iblogs\ib_logfile2 did not exist: new to be created InnoDB: Setting log file c:\iblogs\ib_logfile2 size to 31457280 InnoDB: Doublewrite buffer not found: creating new InnoDB: Doublewrite buffer created InnoDB: creating foreign key constraint system tables InnoDB: foreign key constraint system tables created 011024 10:58:25 InnoDB: Started
For further information about running MySQL on Windows, see section 2.6.2 Windows Notes.
Beginning with MySQL 4.0.11, you can install MySQL on Mac OS X 10.2
("Jaguar") using a Mac OS X PKG binary package instead of the
binary tarball distribution. Please note that older versions of Mac OS X
(e.g. 10.1.x) are not supported by this package!
The package is located inside a disk image (.dmg) file, that you
first need to mount by double-clicking its icon in the Finder. It should
then mount the image and display its contents.
NOTE: Before proceeding with the installation, please make sure that no other MySQL server is running!
Please shut down all running MySQL instances before continuing by either
using the MySQL Manager Application (on Mac OS X Server) or via
mysqladmin shutdown on the command line.
To actually install the MySQL PKG, double click on the package icon. This will launch the Mac OS Package Installer, which will guide you through the installation of MySQL.
The Mac OS X PKG of MySQL will install itself into
`/usr/local/mysql-<version>' and will also install a symbolic link
`/usr/local/mysql', pointing to the new location. If a directory named
`/usr/local/mysql' already exists, it will be renamed to
`/usr/local/mysql.bak' first. Additionally, it will install the mysql
grant tables by executing mysql_install_db after the installation.
The installation layout is similar to the one of the binary distribution, all MySQL binaries are located in directory `/usr/local/mysql/bin'. The MySQL socket will be put into `/etc/mysql.sock' by default. See section 2.2.7 Installation Layouts.
It requires a user account named mysql (which should exist by default
on Mac OS X 10.2 and up).
If you are running Mac OS X Server, you already have a version of MySQL installed:
This manual section covers the installation of the official MySQL Mac OS X PKG only. Make sure to read Apple's help about installing MySQL (Run the "Help View" application, select "Mac OS X Server" help, and do a search for "MySQL" and read the item entitled "Installing MySQL").
Especially note, that the pre-installed version of MySQL on Mac OS X Server
is being started with the command safe_mysqld instead of
mysqld_safe!
If you previously used Marc Liyanage's MySQL packages for Mac OS X from http://www.entropy.ch, you can simply follow the update instructions for packages using the binary installation layout as given on his pages.
If you are upgrading from Marc's version or from the Mac OS X Server version of MySQL to the official MySQL PKG, you also need to convert the existing MySQL privilege tables. See section 2.5.2 Upgrading From Version 3.23 to Version 4.0.
After the installation, you can start up MySQL by running the following commands in a terminal window. Please note that you need to have administrator privileges to perform this task!
shell> cd /usr/local/mysql shell> sudo ./bin/mysqld_safe (Enter your password) (Press CTRL+Z) shell> bg (Press CTRL+D to exit the shell)
You should now be able to connect to the MySQL server, e.g. by running `/usr/local/mysql/bin/mysql'.
To enable the automatic startup of MySQL on bootup, you can download Marc Liyanage's MySQL StartupItem from the following location:
http://www2.entropy.ch/download/mysql-startupitem.pkg.tar.gz
We plan to add a StartupItem to the official MySQL PKG in the near future.
Please note that installing a new MySQL PKG does not remove the directory of an older installation - unfortunately the Mac OS X Installer does not yet offer the functionality required to properly upgrade previously installed packages. After you have copied over the MySQL database files from the previous version and have successfully started the new version, you should consider removing the old installation files to save up disk space. Additionally, you should also remove older versions of the Package Receipt directories located in `/Library/Receipts/mysql-<version>.pkg'.
Check the MySQL homepage (http://www.mysql.com/) for information about the current version and for downloading instructions.
Our main mirror is located at http://mirrors.sunsite.dk/mysql/.
For a complete upto-date list of MySQL web/download mirrors, see http://www.mysql.com/downloads/mirrors.html. There you will also find information about becoming a MySQL mirror site and how to report a bad or out-of-date mirror.
MD5 Checksums or GnuPGAfter you have downloaded the MySQL package that suits your needs and before you attempt to install it, you should make sure it is intact and has not been tampered with.
MySQL AB offers two means of integrity checking: MD5 checksums and
cryptographic signatures using GnuPG, the GNU Privacy Guard.
MD5 ChecksumAfter you have downloaded the package, you should check, if the MD5 checksum matches the one provided on the MySQL download pages. Each package has an individual checksum, that you can verify with the following command:
shell> md5sum <package>
Note, that not all operating systems support the md5sum command - on
some it is simply called md5, others do not ship it at all. On Linux,
it is part of the GNU Text Utilities package, which is available for
a wide range of platforms. You can download the source code from
http://www.gnu.org/software/textutils/ as well. If you have
OpenSSL installed, you can also use the command openssl md5
<package> instead. A DOS/Windows implementation of the md5 command
is available from http://www.fourmilab.ch/md5/.
Example:
shell> md5sum mysql-standard-4.0.10-gamma-pc-linux-i686.tar.gz
155836a7ed8c93aee6728a827a6aa153
mysql-standard-4.0.10-gamma-pc-linux-i686.tar.gz
You should check, if the resulting checksum matches the one printed on the download page right below the respective package.
Most mirror sites also offer a file named `MD5SUMS', which also includes the MD5 checksums for all files included in the `Downloads' directory. Please note however that it's very easy to modify this file and it's not a very reliable method! If in doubt, you should consult different mirror sites and compare the results.
GnuPG
A more reliable method of verifying the integrity of a package is using
cryptographic signatures. MySQL AB uses the GNU Privacy Guard
(GnuPG), an Open Source alternative to the very well-known
Pretty Good Privacy (PGP) by Phil Zimmermann.
See http://www.gnupg.org/ and http://www.openpgp.org/
for more information about OpenPGP/GnuPG and how to obtain
and install GnuPG on your system. Most Linux distributions already
ship with GnuPG installed by default.
Beginning with MySQL 4.0.10 (February 2003), MySQL AB has started signing
their downloadable packages with GnuPG. Cryptographic signatures are
a much more reliable method of verifying the integrity and authenticity of
a file.
To verify the signature for a specific package, you first need to obtain a copy of MySQL AB's public GPG build key build@mysql.com. You can either cut and paste it directly from here, or obtain it from http://www.keyserver.net/.
Key ID:
pub 1024D/5072E1F5 2003-02-03
MySQL Package signing key (www.mysql.com) <build@mysql.com>
Fingerprint: A4A9 4068 76FC BD3C 4567 70C8 8C71 8D3B 5072 E1F5
Public Key (ASCII-armored):
-----BEGIN PGP PUBLIC KEY BLOCK-----
Version: GnuPG v1.0.6 (GNU/Linux)
Comment: For info see http://www.gnupg.org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=YJkx
-----END PGP PUBLIC KEY BLOCK-----
You can import this key into your public GPG keyring by using
gpg --import. See the GPG documentation for more info
on how to work with public keys.
After you have downloaded and imported the public build key, now download your desired MySQL package and the corresponding signature, which is also available from the download page. The signature has the file name extension `.asc'. For example, the signature for `mysql-standard-4.0.10-gamma-pc-linux-i686.tar.gz' would be `mysql-standard-4.0.10-gamma-pc-linux-i686.tar.gz.asc'. Make sure that both files are stored in the same directory and then run the following command to verify the signature for this file:
shell> gpg --verify <package>.asc
Example:
shell> gpg --verify mysql-standard-4.0.10-gamma-pc-linux-i686.tar.gz.asc
gpg: Warning: using insecure memory!
gpg: Signature made Mon 03 Feb 2003 08:50:39 PM MET using DSA key ID 5072E1F5
gpg: Good signature from
"MySQL Package signing key (www.mysql.com) <build@mysql.com>"
The "Good signature" message indicates that everything is all right.
For RPM packages, there is no separate signature - RPM packages
actually have a built-in GPG signature and MD5 checksum. You can
verify them by running the following command:
shell> rpm --checksig <package>.rpm Example: shell> rpm --checksig MySQL-server-4.0.10-0.i386.rpm MySQL-server-4.0.10-0.i386.rpm: md5 gpg OK
Note: If you are using RPM 4.1 and it complains about (GPG)
NOT OK (MISSING KEYS: GPG#5072e1f5) (even though you have imported it into
your GPG public keyring), you need to import the key into the RPM keyring
first. RPM 4.1 does not use your GPG keyring (and GPG itself) anymore, but
rather maintains its own keyring (because it's a system wide application and
the GPG public keyring is user-specific file). To import the MySQL public
key into the RPM keyring, please use the following command:
shell> rpm --import <pubkey> Example: shell> rpm --import mysql_pubkey.asc
In case you notice that the MD5 checksum or GPG signatures
do not match, first try to download the respective package one more time,
maybe from another mirror site. If you repeatedly can not successfully
verify the integrity of the package, please notify us about such incidents
including the full package name and the download site you have been using
at webmaster@mysql.com or build@mysql.com.
We use GNU Autoconf, so it is possible to port MySQL to all modern systems with working Posix threads and a C++ compiler. (To compile only the client code, a C++ compiler is required but not threads.) We use and develop the software ourselves primarily on Sun Solaris (Versions 2.5 - 2.7) and SuSE Linux Version 7.x.
Note that for many operating systems, the native thread support works only in the latest versions. MySQL has been reported to compile successfully on the following operating system/thread package combinations:
glibc 2.0.7+. See section 2.6.1 Linux Notes (All Linux Versions).
Note that not all platforms are suited equally well for running MySQL. How well a certain platform is suited for a high-load mission-critical MySQL server is determined by the following factors:
pthread_mutex_lock() is too anxious to yield CPU time, this will hurt
MySQL tremendously. If this issue is not taken care of, adding extra CPUs
will actually make MySQL slower.
Based on the preceding criteria, the best platforms for running MySQL at this point are x86 with SuSE Linux 7.1, 2.4 kernel, and ReiserFS (or any similar Linux distribution) and SPARC with Solaris 2.7 or 2.8. FreeBSD comes third, but we really hope it will join the top club once the thread library is improved. We also hope that at some point we will be able to include all other platforms on which MySQL compiles, runs okay, but not quite with the same level of stability and performance, into the top category. This will require some effort on our part in cooperation with the developers of the OS/library components MySQL depends upon. If you are interested in making one of those components better, are in a position to influence their development, and need more detailed instructions on what MySQL needs to run better, send an e-mail to internals@lists.mysql.com.
Please note that the preceding comparison is not to say that one OS is better or worse than the other in general. We are talking about choosing a particular OS for a dedicated purpose@-running MySQL, and compare platforms in that regard only. With this in mind, the result of this comparison would be different if we included more issues into it. And in some cases, the reason one OS is better than the other could simply be that we have put forth more effort into testing on and optimising for that particular platform. We are just stating our observations to help you decide on which platform to use MySQL on in your setup.
The first decision to make is whether you want to use the latest development release or the last stable release:
The second decision to make is whether you want to use a source distribution or a binary distribution. In most cases you should probably use a binary distribution, if one exists for your platform, as this generally will be easier to install than a source distribution.
In the following cases you probably will be better off with a source installation:
MySQL
clients can connect to both MySQL versions.
The extended MySQL binary distribution is marked with the
-max suffix and is configured with the same options as
mysqld-max. See section 4.7.5 mysqld-max, An Extended mysqld Server.
If you want to use the MySQL-Max RPM, you must first
install the standard MySQL RPM.
mysqld with some extra features that are
not in the standard binary distributions. Here is a list of the most
common extra options that you may want to use:
--with-innodb
--with-berkeley-db
--with-raid
--with-libwrap
--with-named-z-lib (This is done for some of the binaries)
--with-debug[=full]
pgcc), or use compiler options that are better optimised for your
processor.
The MySQL naming scheme uses release numbers that consist of three
numbers and a suffix. For example, a release name like
mysql-3.21.17-beta is interpreted like this:
3) describes the file format. All Version 3
releases have the same file format.
21) is the release level. Normally there are two to
choose from. One is the release/stable branch (currently 23) and the
other is the development branch (currently 4.0). Normally both are
stable, but the development version may have quirks, may be missing documentation on
new features, or may fail to compile on some systems.
17) is the version number within the
release level. This is incremented for each new distribution. Usually you
want the latest version for the release level you have chosen.
beta) indicates the stability level of the release.
The possible suffixes are:
alpha indicates that the release contains some large section of
new code that hasn't been 100% tested. Known bugs (usually there are none)
should be documented in the News section. See section D MySQL Change History. There are also new
commands and extensions in most alpha releases. Active development that
may involve major code changes can occur on an alpha release, but everything
will be tested before doing a release. There should be no known bugs in any
MySQL release.
beta means that all new code has been tested. No major new
features that could cause corruption on old code are added. There should
be no known bugs. A version changes from alpha to beta when there
haven't been any reported fatal bugs within an alpha version for at least
a month and we don't plan to add any features that could make any old command
more unreliable.
gamma is a beta that has been around a while and seems to work fine.
Only minor fixes are added. This is what many other companies call a release.
All versions of MySQL are run through our standard tests and benchmarks to ensure that they are relatively safe to use. Because the standard tests are extended over time to check for all previously found bugs, the test suite keeps getting better.
Note that all releases have been tested at least with:
crash-me test
Another test is that we use the newest MySQL version in our internal production environment, on at least one machine. We have more than 100 gigabytes of data to work with.
This section describes the default layout of the directories created by installing binary and source distributions.
A binary distribution is installed by unpacking it at the installation location you choose (typically `/usr/local/mysql') and creates the following directories in that location:
| Directory | Contents of directory |
| `bin' | Client programs and the mysqld server
|
| `data' | Log files, databases |
| `include' | Include (header) files |
| `lib' | Libraries |
| `scripts' | mysql_install_db
|
| `share/mysql' | Error message files |
| `sql-bench' | Benchmarks |
A source distribution is installed after you configure and compile it. By default, the installation step installs files under `/usr/local', in the following subdirectories:
| Directory | Contents of directory |
| `bin' | Client programs and scripts |
| `include/mysql' | Include (header) files |
| `info' | Documentation in Info format |
| `lib/mysql' | Libraries |
| `libexec' | The mysqld server
|
| `share/mysql' | Error message files |
| `sql-bench' | Benchmarks and crash-me test
|
| `var' | Databases and log files |
Within an installation directory, the layout of a source installation differs from that of a binary installation in the following ways:
mysqld server is installed in the `libexec'
directory rather than in the `bin' directory.
mysql_install_db is installed in the `/usr/local/bin' directory
rather than in `/usr/local/mysql/scripts'.
You can create your own binary installation from a compiled source distribution by executing the script `scripts/make_binary_distribution'.
MySQL is evolving quite rapidly here at MySQL AB and we want to share this with other MySQL users. We try to make a release when we have very useful features that others seem to have a need for.
We also try to help out users who request features that are easy to implement. We take note of what our licensed users want to have, and we especially take note of what our extended e-mail supported customers want and try to help them out.
No one has to download a new release. The News section will tell you if the new release has something you really want. See section D MySQL Change History.
We use the following policy when updating MySQL:
The current stable release is Version 3.23; we have already moved active development to Version 4.0. Bugs will still be fixed in the stable version. We don't believe in a complete freeze, as this also leaves out bug fixes and things that ``must be done.'' ``Somewhat frozen'' means that we may add small things that ``almost surely will not affect anything that's already working.''
MySQL uses a slightly different naming scheme from most other products. In general it's relatively safe to use any version that has been out for a couple of weeks without being replaced with a new version. See section 2.2.6 Which MySQL Version to Use.
As a service, we at MySQL AB provide a set of binary distributions of MySQL that are compiled at our site or at sites where customers kindly have given us access to their machines.
These distributions are generated using the script
Build-tools/Do-compile which compiles the source code and creates the
binary tar.gz archive using scripts/make_binary_distribution
These binaries are configured and built with the following compilers and
options.
Binaries built on MySQL AB development systems:
gcc 2.95.3
CFLAGS="-O2 -mcpu=pentiumpro" CXX=gcc CXXFLAGS="-O2 -mcpu=pentiumpro -felide-constructors" ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile --enable-assembler --disable-shared --with-client-ldflags=-all-static --with-mysqld-ldflags=-all-static
ecc (Intel C++ Itanium Compiler 7.0)
CC=ecc CFLAGS=-tpp1 CXX=ecc CXXFLAGS=-tpp1 ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile
ccc (Compaq C V6.2-505 / Compaq C++ V6.3-006)
CC=ccc CFLAGS="-fast -arch generic" CXX=cxx CXXFLAGS="-fast -arch generic -noexceptions -nortti" ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile --with-mysqld-ldflags=-non_shared --with-client-ldflags=-non_shared --disable-shared
egcs 1.1.2
CC=gcc CFLAGS="-O3 -fno-omit-frame-pointer" CXX=gcc CXXFLAGS="-O3 -fno-omit-frame-pointer -felide-constructors -fno-exceptions -fno-rtti" ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile --enable-assembler --disable-shared
gcc 2.95.3
CFLAGS="-O2" CXX=gcc CXXFLAGS="-O2 -felide-constructors" ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile --disable-shared --with-client-ldflags=-all-static --with-mysqld-ldflags=-all-static
gcc 3.2
CC=gcc CFLAGS="-O3 -fno-omit-frame-pointer" CXX=gcc CXXFLAGS="-O3 -fno-omit-frame-pointer -felide-constructors -fno-exceptions -fno-rtti" ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile --enable-assembler --with-named-z-libs=no --with-named-curses-libs=-lcurses --disable-shared
gcc 2.95.3
CC=gcc CFLAGS="-O3 -fno-omit-frame-pointer" CXX=gcc CXXFLAGS="-O3 -fno-omit-frame-pointer -felide-constructors -fno-exceptions -fno-rtti" ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile --enable-assembler --with-named-curses-libs=-lcurses --disable-shared
cc-5.0 (Sun Forte 5.0)
CC=cc-5.0 CXX=CC ASFLAGS="-xarch=v9" CFLAGS="-Xa -xstrconst -mt -D_FORTEC_ -xarch=v9" CXXFLAGS="-noex -mt -D_FORTEC_ -xarch=v9" ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile --enable-assembler --with-named-z-libs=no --enable-thread-safe-client --disable-shared
gcc 3.2.1
CFLAGS="-O2 -mcpu=powerpc -Wa,-many " CXX=gcc CXXFLAGS="-O2 -mcpu=powerpc -Wa,-many -felide-constructors -fno-exceptions -fno-rtti" ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile --with-named-z-libs=no --disable-shared
gcc 3.2.1
CFLAGS="-O2 -mcpu=powerpc -Wa,-many" CXX=gcc CXXFLAGS="-O2 -mcpu=powerpc -Wa,-many -felide-constructors -fno-exceptions -fno-rtti" ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex --with-server-suffix="-pro" --enable-thread-safe-client --enable-local-infile --with-named-z-libs=no --disable-shared --with-innodb
gcc 3.1
CFLAGS="-DHPUX -I/opt/dce/include -O3 -fPIC" CXX=gcc CXXFLAGS="-DHPUX -I/opt/dce /include -felide-constructors -fno-exceptions -fno-rtti -O3 -fPIC" ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile --with-pthread --with-named-thread-libs=-ldce --with-lib-ccflags=-fPIC --disable-shared
aCC (HP ANSI C++ B3910B A.03.33)
CC=cc CXX=aCC CFLAGS=+DD64 CXXFLAGS=+DD64 ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile --disable-shared
gcc 3.1
CC=gcc CFLAGS="-O3 -fno-omit-frame-pointer" CXX=gcc CXXFLAGS="-O3 -fno-omit-frame-pointer -felide-constructors -fno-exceptions -fno-rtti" ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile --disable-shared
gcc 2.95.4
CFLAGS=-DHAVE_BROKEN_REALPATH ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile --enable-assembler --with-named-z-libs=not-used --disable-shared
The following binaries are built on third-party systems kindly provided to MySQL AB by other users. Please note that these are only provided as a courtesy. Since MySQL AB does not have full control over these systems, we can only provide limited support for the binaries built on these systems.
gcc 2.95.3
CFLAGS="-O3 -mpentium" LDFLAGS=-static CXX=gcc CXXFLAGS="-O3 -mpentium -felide-constructors" ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile --with-named-z-libs=no --enable-thread-safe-client --disable-shared
CC 3.2
CC=cc CFLAGS="-O" CXX=CC ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile --with-named-z-libs=no --enable-thread-safe-client --disable-shared
cc/cxx (Compaq C V6.3-029i / DIGITAL C++ V6.1-027)
CC="cc -pthread" CFLAGS="-O4 -ansi_alias -ansi_args -fast -inline speed -speculate all" CXX="cxx -pthread" CXXFLAGS="-O4 -ansi_alias -fast -inline speed -speculate all -noexceptions -nortti" ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile --with-prefix=/usr/local/mysql --with-named-thread-libs="-lpthread -lmach -lexc -lc" --disable-shared --with-mysqld-ldflags=-all-static
gcc 3.0.1
CC=gcc CFLAGS="-O3 -fno-omit-frame-pointer" CXXFLAGS="-O3 -fno-omit-frame-pointer -felide-constructors -fno-exceptions -fno-rtti" ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile --disable-shared
The following compile options have been used for binary packages MySQL AB used to provide in the past. These binaries are currently not being updated anymore, but the compile options are kept in here for reference purposes.
gcc 2.95.2
CFLAGS="-O3 -mpentiumpro" CXX=gcc CXXFLAGS="-O3 -mpentiumpro -felide-constructors -fno-exceptions -fno-rtti" ./configure --prefix=/usr/local/mysql --enable-assembler --with-mysqld-ldflags=-all-static --disable-shared --with-extra-charsets=complex
gcc 2.7.2.1
CC=gcc CXX=gcc CXXFLAGS="-O3 -felide-constructors" ./configure --prefix=/usr/local/mysql --disable-shared --with-extra-charsets=complex --enable-assembler
egcs 1.0.3a or 2.90.27 or gcc 2.95.2 and newer
CC=gcc CFLAGS="-O3" CXX=gcc CXXFLAGS="-O3 -felide-constructors -fno-exceptions -fno-rtti" ./configure --prefix=/usr/local/mysql --with-low-memory --with-extra-charsets=complex --enable-assembler
gcc 2.8.1
CC=gcc CXX=gcc CXXFLAGS=-O3 ./configure --prefix=/usr/local/mysql --with-low-memory --with-extra-charsets=complex
gcc 2.7.2.1
CC=gcc CXX=gcc CXXFLAGS=-O ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex
gcc 2.7.2
CC=gcc CXX=gcc CXXFLAGS=-O3 ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex
gcc 2.7.2.2
CC=gcc CXX=gcc CXXFLAGS=-O3 ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex
Anyone who has more optimal options for any of the preceding configurations listed can always mail them to the developer's mailing list at internals@lists.mysql.com.
RPM distributions prior to MySQL Version 3.22 are user-contributed. Beginning with Version 3.22, the RPMs are generated by us at MySQL AB.
If you want to compile a debug version of MySQL, you should add
--with-debug or --with-debug=full to the preceding configure lines
and remove any -fomit-frame-pointer options.
For the Windows distribution, please see section 2.1.2 Installing MySQL on Windows.
See also section 2.1.2.1 Installing the Binaries, section 2.1.1 Installing MySQL on Linux, and section 8.4.7 Building Client Programs.
You need the following tools to install a MySQL binary distribution:
gunzip to uncompress the distribution.
tar to unpack the distribution. GNU tar is
known to work. Sun tar is known to have problems.
An alternative installation method under Linux is to use RPM-based (RPM Package Manager) distributions. See section 2.1.1 Installing MySQL on Linux.
If you run into problems, please always use mysqlbug when
posting questions to mysql@lists.mysql.com. Even if the problem
isn't a bug, mysqlbug gathers system information that will help others
solve your problem. By not using mysqlbug, you lessen the likelihood
of getting a solution to your problem! You will find mysqlbug in the
`bin' directory after you unpack the distribution. See section 1.6.1.3 How to Report Bugs or Problems.
The basic commands you must execute to install and use a MySQL binary distribution are:
shell> groupadd mysql shell> useradd -g mysql mysql shell> cd /usr/local shell> gunzip < /path/to/mysql-VERSION-OS.tar.gz | tar xvf - shell> ln -s full-path-to-mysql-VERSION-OS mysql shell> cd mysql shell> scripts/mysql_install_db shell> chown -R root . shell> chown -R mysql data shell> chgrp -R mysql . shell> bin/safe_mysqld --user=mysql & or shell> bin/mysqld_safe --user=mysql & if you are running MySQL 4.x
You can add new users using the bin/mysql_setpermission script if
you install the DBI and Msql-Mysql-modules Perl modules.
A more detailed description follows.
To install a binary distribution, follow these steps, then proceed to section 2.4 Post-installation Setup and Testing, for post-installation setup and testing:
root.)
tar
archives and have names like `mysql-VERSION-OS.tar.gz', where
VERSION is a number (for example, 3.21.15), and OS
indicates the type of operating system for which the distribution is intended
(for example, pc-linux-gnu-i586).
-max suffix, this
means that the binary has support for transaction-safe tables and other
features. See section 4.7.5 mysqld-max, An Extended mysqld Server. Note that all binaries
are built from the same MySQL source distribution.
mysqld to run as:
shell> groupadd mysql shell> useradd -g mysql mysqlThese commands add the
mysql group and the mysql user. The
syntax for useradd and groupadd may differ slightly on different
versions of Unix. They may also be called adduser and addgroup.
You may wish to call the user and group something else instead of mysql.
shell> cd /usr/local
shell> gunzip < /path/to/mysql-VERSION-OS.tar.gz | tar xvf - shell> ln -s full-path-to-mysql-VERSION-OS mysqlThe first command creates a directory named `mysql-VERSION-OS'. The second command makes a symbolic link to that directory. This lets you refer more easily to the installation directory as `/usr/local/mysql'.
shell> cd mysqlYou will find several files and subdirectories in the
mysql directory.
The most important for installation purposes are the `bin' and
`scripts' subdirectories.
PATH environment variable so that your shell finds the MySQL
programs properly. See section F Environment Variables.
mysql_install_db script used to initialise
the mysql database containing the grant tables that store the server
access permissions.
mysqlaccess and have the MySQL
distribution in some non-standard place, you must change the location where
mysqlaccess expects to find the mysql client. Edit the
`bin/mysqlaccess' script at approximately line 18. Search for a line
that looks like this:
$MYSQL = '/usr/local/bin/mysql'; # path to mysql executableChange the path to reflect the location where
mysql actually is
stored on your system. If you do not do this, you will get a Broken
pipe error when you run mysqlaccess.
shell> scripts/mysql_install_dbNote that MySQL versions older than Version 3.22.10 started the MySQL server when you run
mysql_install_db. This is no
longer true!
root and ownership of the data
directory to the user that you will run mysqld as:
shell> chown -R root /usr/local/mysql/. shell> chown -R mysql /usr/local/mysql/data shell> chgrp -R mysql /usr/local/mysql/.The first command changes the
owner attribute of the files to the
root user, the second one changes the owner attribute of the
data directory to the mysql user, and the third one changes the
group attribute to the mysql group.
DBI/DBD interface,
see section 2.7 Perl Installation Comments.
support-files/mysql.server to the location where
your system has its startup files. More information can be found in the
support-files/mysql.server script itself and in
section 2.4.3 Starting and Stopping MySQL Automatically.
After everything has been unpacked and installed, you should initialise and test your distribution.
You can start the MySQL server with the following command:
shell> bin/safe_mysqld --user=mysql &
Now proceed to section 4.7.2 safe_mysqld, The Wrapper Around mysqld, and
See section 2.4 Post-installation Setup and Testing.
Before you proceed with the source installation, check first to see if our binary is available for your platform and if it will work for you. We put a lot of effort into making sure that our binaries are built with the best possible options.
You need the following tools to build and install MySQL from source:
gunzip to uncompress the distribution.
tar to unpack the distribution. GNU tar is
known to work. Sun tar is known to have problems.
gcc >= 2.95.2, egcs >= 1.0.2
or egcs 2.91.66, SGI C++, and SunPro C++ are some of the
compilers that are known to work. libg++ is not needed when
using gcc. gcc 2.7.x has a bug that makes it impossible
to compile some perfectly legal C++ files, such as
`sql/sql_base.cc'. If you only have gcc 2.7.x, you must
upgrade your gcc to be able to compile MySQL. gcc
2.8.1 is also known to have problems on some platforms, so it should be
avoided if a new compiler exists for the platform.
gcc >= 2.95.2 is recommended when compiling MySQL
Version 3.23.x.
make program. GNU make is always recommended and is
sometimes required. If you have problems, we recommend trying GNU
make 3.75 or newer.
If you are using a recent version of gcc, recent enough to understand the
-fno-exceptions option, it is very important that you use
it. Otherwise, you may compile a binary that crashes randomly. We also
recommend that you use -felide-constructors and -fno-rtti along
with -fno-exceptions. When in doubt, do the following:
CFLAGS="-O3" CXX=gcc CXXFLAGS="-O3 -felide-constructors -fno-exceptions \
-fno-rtti" ./configure --prefix=/usr/local/mysql --enable-assembler \
--with-mysqld-ldflags=-all-static
On most systems this will give you a fast and stable binary.
If you run into problems, please always use mysqlbug when
posting questions to mysql@lists.mysql.com. Even if the problem
isn't a bug, mysqlbug gathers system information that will help others
solve your problem. By not using mysqlbug, you lessen the likelihood
of getting a solution to your problem! You will find mysqlbug in the
`scripts' directory after you unpack the distribution.
See section 1.6.1.3 How to Report Bugs or Problems.
The basic commands you must execute to install a MySQL source distribution are:
shell> groupadd mysql shell> useradd -g mysql mysql shell> gunzip < mysql-VERSION.tar.gz | tar -xvf - shell> cd mysql-VERSION shell> ./configure --prefix=/usr/local/mysql shell> make shell> make install shell> scripts/mysql_install_db shell> chown -R root /usr/local/mysql shell> chown -R mysql /usr/local/mysql/var shell> chgrp -R mysql /usr/local/mysql shell> cp support-files/my-medium.cnf /etc/my.cnf shell> /usr/local/mysql/bin/safe_mysqld --user=mysql & or shell> /usr/local/mysql/bin/mysqld_safe --user=mysql & if you are running MySQL 4.x.
If you want to have support for InnoDB tables, you should edit the
/etc/my.cnf file and remove the # character before the
parameter that starts with innodb_....
See section 4.1.2 `my.cnf' Option Files, and section 7.5.2 InnoDB Startup Options.
If you start from a source RPM, do the following:
shell> rpm --rebuild --clean MySQL-VERSION.src.rpm
This will make a binary RPM that you can install.
You can add new users using the bin/mysql_setpermission script if
you install the DBI and Msql-Mysql-modules Perl modules.
A more detailed description follows.
To install a source distribution, follow these steps, then proceed to section 2.4 Post-installation Setup and Testing, for post-installation initialisation and testing:
BDB or BerkeleyDB Tables.
MySQL source distributions are provided as compressed tar
archives and have names like `mysql-VERSION.tar.gz', where
VERSION is a number like 3.23.56.
mysqld to run as:
shell> groupadd mysql shell> useradd -g mysql mysqlThese commands add the
mysql group and the mysql user. The
syntax for useradd and groupadd may differ slightly on different
versions of Unix. They may also be called adduser and addgroup.
You may wish to call the user and group something else instead of mysql.
shell> gunzip < /path/to/mysql-VERSION.tar.gz | tar xvf -This command creates a directory named `mysql-VERSION'.
shell> cd mysql-VERSIONNote that currently you must configure and build MySQL from this top-level directory. You cannot build it in a different directory.
shell> ./configure --prefix=/usr/local/mysql shell> makeWhen you run
configure, you might want to specify some options.
Run ./configure --help for a list of options.
section 2.3.3 Typical configure Options, discusses some of the
more useful options.
If configure fails, and you are going to send mail to
mysql@lists.mysql.com to ask for assistance, please include any
lines from `config.log' that you think can help solve the problem. Also
include the last couple of lines of output from configure if
configure aborts. Post the bug report using the mysqlbug
script. See section 1.6.1.3 How to Report Bugs or Problems.
If the compile fails, see section 2.3.5 Problems Compiling MySQL?, for help with
a number of common problems.
shell> make installYou might need to run this command as
root.
shell> scripts/mysql_install_dbNote that MySQL versions older than Version 3.22.10 started the MySQL server when you run
mysql_install_db. This is no
longer true!
root and ownership of the data
directory to the user that you will run mysqld as:
shell> chown -R root /usr/local/mysql shell> chown -R mysql /usr/local/mysql/var shell> chgrp -R mysql /usr/local/mysqlThe first command changes the
owner attribute of the files to the
root user, the second one changes the owner attribute of the
data directory to the mysql user, and the third one changes the
group attribute to the mysql group.
DBI/DBD interface,
see section 2.7 Perl Installation Comments.
support-files/mysql.server to the location where
your system has its startup files. More information can be found in the
support-files/mysql.server script itself and in
section 2.4.3 Starting and Stopping MySQL Automatically.
After everything has been installed, you should initialise and test your distribution:
shell> /usr/local/mysql/bin/safe_mysqld --user=mysql &
If that command fails immediately with mysqld daemon ended, you can
find some information in the file `mysql-data-directory/'hostname'.err'.
The likely reason is that you already have another mysqld server
running. See section 4.1.4 Running Multiple MySQL Servers on the Same Machine.
Now proceed to section 2.4 Post-installation Setup and Testing.
Sometimes patches appear on the mailing list or are placed in the patches area of the MySQL web site (http://www.mysql.com/downloads/patches.html).
To apply a patch from the mailing list, save the message in which the patch appears in a file, change into the top-level directory of your MySQL source tree, and run these commands:
shell> patch -p1 < patch-file-name shell> rm config.cache shell> make clean
Patches from the FTP site are distributed as plain text files or as files
compressed with gzip. Apply a plain patch as shown
previously for
mailing list patches. To apply a compressed patch, change into the
top-level directory of your MySQL source tree and run these
commands:
shell> gunzip < patch-file-name.gz | patch -p1 shell> rm config.cache shell> make clean
After applying a patch, follow the instructions for a normal source install,
beginning with the ./configure step. After running the make
install step, restart your MySQL server.
You may need to bring down any currently running server before you run
make install. (Use mysqladmin shutdown to do this.) Some
systems do not allow you to install a new version of a program if it replaces
the version that is currently executing.
configure Options
The configure script gives you a great deal of control over how
you configure your MySQL distribution. Typically you do this
using options on the configure command-line. You can also affect
configure using certain environment variables. See section F Environment Variables. For a list of options supported by configure, run
this command:
shell> ./configure --help
Some of the more commonly-used configure options are described here:
--without-server option:
shell> ./configure --without-serverIf you don't have a C++ compiler,
mysql will not compile (it is the
one client program that requires C++). In this case,
you can remove the code in configure that tests for the C++ compiler
and then run ./configure with the --without-server option. The
compile step will still try to build mysql, but you can ignore any
warnings about `mysql.cc'. (If make stops, try make -k
to tell it to continue with the rest of the build even if errors occur.)
libmysqld.a) you should
use the --with-embedded-server option.
configure command, something like one
of these:
shell> ./configure --prefix=/usr/local/mysql
shell> ./configure --prefix=/usr/local \
--localstatedir=/usr/local/mysql/data
The first command changes the installation prefix so that everything is
installed under `/usr/local/mysql' rather than the default of
`/usr/local'. The second command preserves the default installation
prefix, but overrides the default location for database directories
(normally `/usr/local/var') and changes it to
/usr/local/mysql/data. After you have compiled MySQL, you can
change these options with option files. See section 4.1.2 `my.cnf' Option Files.
configure command like this:
shell> ./configure --with-unix-socket-path=/usr/local/mysql/tmp/mysql.sockNote that the given file must be an absolute pathname! You can also later change the location `mysql.sock' by using the MySQL option files. See section A.4.5 How to Protect or Change the MySQL Socket File `/tmp/mysql.sock'.
configure like this:
shell> ./configure --with-client-ldflags=-all-static \
--with-mysqld-ldflags=-all-static
gcc and don't have libg++ or libstdc++
installed, you can tell configure to use gcc as your C++
compiler:
shell> CC=gcc CXX=gcc ./configureWhen you use
gcc as your C++ compiler, it will not attempt to link in
libg++ or libstdc++. This may be a good idea to do even if you
have the above libraries installed, as some versions of these libraries have
caused strange problems for MySQL users in the past.
Here are some common environment variables to set depending on
the compiler you are using:
| Compiler | Recommended options |
| gcc 2.7.2.1 | CC=gcc CXX=gcc CXXFLAGS="-O3 -felide-constructors" |
| egcs 1.0.3a | CC=gcc CXX=gcc CXXFLAGS="-O3 -felide-constructors -fno-exceptions -fno-rtti" |
| gcc 2.95.2 | CFLAGS="-O3 -mpentiumpro" CXX=gcc CXXFLAGS="-O3 -mpentiumpro \ -felide-constructors -fno-exceptions -fno-rtti" |
| pgcc 2.90.29 or newer | CFLAGS="-O3 -mpentiumpro -mstack-align-double" CXX=gcc \ CXXFLAGS="-O3 -mpentiumpro -mstack-align-double -felide-constructors \ -fno-exceptions -fno-rtti" |
--prefix=/usr/local/mysql --enable-assembler \ --with-mysqld-ldflags=-all-staticThe full configure line would, in other words, be something like the following for all recent gcc versions:
CFLAGS="-O3 -mpentiumpro" CXX=gcc CXXFLAGS="-O3 -mpentiumpro \ -felide-constructors -fno-exceptions -fno-rtti" ./configure \ --prefix=/usr/local/mysql --enable-assembler \ --with-mysqld-ldflags=-all-staticThe binaries we provide on the MySQL web site at http://www.mysql.com/ are all compiled with full optimisation and should be perfect for most users. See section 2.2.9 MySQL Binaries Compiled by MySQL AB. There are some things you can tweak to make an even faster binary, but this is only for advanced users. See section 5.5.3 How Compiling and Linking Affects the Speed of MySQL. If the build fails and produces errors about your compiler or linker not being able to create the shared library `libmysqlclient.so.#' (`#' is a version number), you can work around this problem by giving the
--disable-shared option to configure. In this case,
configure will not build a shared `libmysqlclient.so.#' library.
DEFAULT column values for
non-NULL columns (that is, columns that are not allowed to be
NULL). This causes INSERT statements to generate an error
unless you explicitly specify values for all columns that require a
non-NULL value. To suppress use of default values, run
configure like this:
shell> CXXFLAGS=-DDONT_USE_DEFAULT_FIELDS ./configure
--with-charset option:
shell> ./configure --with-charset=CHARSET
CHARSET may be one of big5, cp1251, cp1257,
czech, danish, dec8, dos, euc_kr,
gb2312, gbk, german1, hebrew, hp8,
hungarian, koi8_ru, koi8_ukr, latin1,
latin2, sjis, swe7, tis620, ujis,
usa7, or win1251ukr.
See section 4.6.1 The Character Set Used for Data and Sorting.
If you want to convert characters between the server and the client,
you should take a look at the SET CHARACTER SET command.
See section 5.5.6 SET Syntax.
Warning: If you change character sets after having created any
tables, you will have to run myisamchk -r -q --set-character-set=charset
on every table. Your
indexes may be sorted incorrectly otherwise. (This can happen if you
install MySQL, create some tables, then reconfigure
MySQL to use a different character set and reinstall it.)
With the option --with-extra-charsets=LIST you can define
which additional character sets should be compiled into the server.
Here LIST is either a list of character
sets separated with spaces,
complex to include all characters that can't be dynamically loaded,
or all to include all character sets into the binaries.
--with-debug
option:
shell> ./configure --with-debugThis causes a safe memory allocator to be included that can find some errors and that provides output about what is happening. See section E.1 Debugging a MySQL server.
--enable-thread-safe-client configure options. This will create a
libmysqlclient_r library with which you should link your threaded
applications. See section 8.4.8 How to Make a Threaded Client.
Caution: You should read this section only if you are interested in helping us test our new code. If you just want to get MySQL up and running on your system, you should use a standard release distribution (either a source or binary distribution will do).
To obtain our most recent development source tree, use these instructions:
BitKeeper from
http://www.bitmover.com/cgi-bin/download.cgi. You will need
Bitkeeper 3.0 or newer to access our repository.
BitKeeper is installed, first go to the directory you
want to work from, and then use one of the following commands to clone
the MySQL version branch of your choice:
To clone the 3.23 branch, use this command:
shell> bk clone bk://mysql.bkbits.net/mysql-3.23 mysql-3.23To clone the 4.0 branch, use this command:
shell> bk clone bk://mysql.bkbits.net/mysql-4.0 mysql-4.0To clone the 4.1 branch, use this command:
shell> bk clone bk://mysql.bkbits.net/mysql-4.1 mysql-4.1In the preceding examples the source tree will be set up in the `mysql-3.23/', `mysql-4.0/', or `mysql-4.1/' subdirectory of your current directory. If you are behind a firewall and can only initiate HTTP connections, you can also use
BitKeeper via HTTP.
If you are required to use a proxy server, simply set the environment
variable http_proxy to point to your proxy:
shell> export http_proxy="http://your.proxy.server:8080/"Now, simply replace the
bk:// with http:// when doing
a clone. Example:
shell> bk clone http://mysql.bkbits.net/mysql-4.1 mysql-4.1The initial download of the source tree may take a while, depending on the speed of your connection - please be patient.
make, autoconf 2.53 (or newer),
automake 1.5, libtool 1.4, and m4 to run the next
set of commands. Note that automake 1.7 or newer doesn't yet work.
If you are using trying to configure MySQL 4.1 you will also need
bison 1.75. Older versions of bison may report this error:
sql_yacc.yy:#####: fatal error: maximum table size (32767)
exceeded. Note: the maximum table size is not actually exceeded,
the error is caused by bugs in these earlier bison versions.
The typical command to do in a shell is:
cd mysql-4.0 bk -r get -Sq aclocal; autoheader; autoconf; automake (cd innobase ; aclocal; autoheader; autoconf; automake) # for InnoDB (cd bdb/dist ; sh s_all ) # for Berkeley DB ./configure # Add your favorite options here makeIf you get some strange error during this stage, check that you really have
libtool installed!
A collection of our standard configure scripts is located in the
`BUILD/' subdirectory. If you are lazy, you can use
`BUILD/compile-pentium-debug'. To compile on a different architecture,
modify the script by removing flags that are Pentium-specific.
make install. Be careful with this
on a production machine; the command may overwrite your live release
installation. If you have another installation of MySQL, we
recommand that you run ./configure with different values for the
prefix, with-tcp-port, and unix-socket-path options than
those used for your production server.
make test. See section 9.1.2 MySQL Test Suite.
make stage and the distribution does
not compile, please report it to bugs@lists.mysql.com. If you
have installed the latest versions of the required GNU tools, and they
crash trying to process our configuration files, please report that also.
However, if you execute aclocal and get a command not found
error or a similar problem, do not report it. Instead, make sure all
the necessary tools are installed and that your PATH variable is
set correctly so that your shell can find them.
bk clone operation to get the source tree, you
should run bk pull periodically to get the updates.
bk sccstool. If you see some funny diffs or code that you have a
question about, do not hesitate to send e-mail to
internals@lists.mysql.com. Also, if you think you have a better idea
on how to do something, send an e-mail to the same address with a patch.
bk diffs will produce a patch for you after you have made changes
to the source. If you do not have the time to code your idea, just send
a description.
BitKeeper has a nice help utility that you can access via
bk helptool.
bk ci or bk citool) will
trigger the posting of a message with the changeset to our internals
mailing list, as well as the usual openlogging.org submission with
just the changeset comments.
Generally, you wouldn't need to use commit (since the public tree will
not allow bk push), but rather use the bk diffs method
described previously.
You can also browse changesets, comments and sourcecode online by browsing to e.g. http://mysql.bkbits.net:8080/mysql-4.1 For MySQL 4.1.
The manual is in a separate tree which can be cloned with:
shell> bk clone bk://mysql.bkbits.net/mysqldoc mysqldoc
All MySQL programs compile cleanly for us with no warnings on
Solaris or Linux using gcc. On other systems, warnings may occur due to
differences in system include files. See section 2.3.6 MIT-pthreads Notes for warnings
that may occur when using MIT-pthreads. For other problems, check
the following list.
The solution to many problems involves reconfiguring. If you do need to reconfigure, take note of the following:
configure is run after it already has been run, it may use
information that was gathered during its previous invocation. This
information is stored in `config.cache'. When configure starts
up, it looks for that file and reads its contents if it exists, on the
assumption that the information is still correct. That assumption is invalid
when you reconfigure.
configure, you must run make again
to recompile. However, you may want to remove old object files from previous
builds first because they were compiled using different configuration options.
To prevent old configuration information or object files from being used,
run these commands before rerunning configure:
shell> rm config.cache shell> make clean
Alternatively, you can run make distclean.
The following list describes some of the problems when compiling MySQL that have been found to occur most often:
Internal compiler error: program cc1plus got fatal signal 11 or Out of virtual memory or Virtual memory exhaustedThe problem is that
gcc requires huge amounts of memory to compile
`sql_yacc.cc' with inline functions. Try running configure with
the --with-low-memory option:
shell> ./configure --with-low-memoryThis option causes
-fno-inline to be added to the compile line if you
are using gcc and -O0 if you are using something else. You
should try the --with-low-memory option even if you have so much
memory and swap space that you think you can't possibly have run out. This
problem has been observed to occur even on systems with generous hardware
configurations, and the --with-low-memory option usually fixes it.
configure picks c++ as the compiler name and
GNU c++ links with -lg++. If you are using gcc,
that behaviour can cause problems during configuration such as this:
configure: error: installation or configuration problem: C++ compiler cannot create executables.You might also observe problems during compilation related to
g++, libg++, or libstdc++.
One cause of these problems is that you may not have g++, or you may
have g++ but not libg++, or libstdc++. Take a look at
the `config.log' file. It should contain the exact reason why your c++
compiler didn't work! To work around these problems, you can use gcc
as your C++ compiler. Try setting the environment variable CXX to
"gcc -O3". For example:
shell> CXX="gcc -O3" ./configureThis works because
gcc compiles C++ sources as well as g++
does, but does not link in libg++ or libstdc++ by default.
Another way to fix these problems, of course, is to install g++,
libg++, and libstdc++. We would however like to recommend
you to not use libg++ or libstdc++ with MySQL as this will
only increase the binary size of mysqld without giving you any benefits.
Some versions of these libraries have also caused strange problems for
MySQL users in the past.
make to GNU make:
making all in mit-pthreads make: Fatal error in reader: Makefile, line 18: Badly formed macro assignment or make: file `Makefile' line 18: Must be a separator (: or pthread.h: No such file or directorySolaris and FreeBSD are known to have troublesome
make programs.
GNU make Version 3.75 is known to work.
CFLAGS and CXXFLAGS environment
variables. You can also specify the compiler names this way using CC
and CXX. For example:
shell> CC=gcc shell> CFLAGS=-O3 shell> CXX=gcc shell> CXXFLAGS=-O3 shell> export CC CFLAGS CXX CXXFLAGSSee section 2.2.9 MySQL Binaries Compiled by MySQL AB, for a list of flag definitions that have been found to be useful on various systems.
gcc compiler:
client/libmysql.c:273: parse error before `__attribute__'
gcc 2.8.1 is known to work, but we recommend using gcc 2.95.2 or
egcs 1.0.3a instead.
mysqld,
configure didn't correctly detect the type of the last argument to
accept(), getsockname(), or getpeername():
cxx: Error: mysqld.cc, line 645: In this statement, the referenced
type of the pointer value "&length" is "unsigned long", which
is not compatible with "int".
new_sock = accept(sock, (struct sockaddr *)&cAddr, &length);
To fix this, edit the `config.h' file (which is generated by
configure). Look for these lines:
/* Define as the base type of the last arg to accept */ #define SOCKET_SIZE_TYPE XXXChange
XXX to size_t or int, depending on your
operating system. (Note that you will have to do this each time you run
configure because configure regenerates `config.h'.)
"sql_yacc.yy", line xxx fatal: default action causes potential...This is a sign that your version of
yacc is deficient.
You probably need to install bison (the GNU version of yacc)
and use that instead.
mysqld or a MySQL client, run
configure with the --with-debug option, then recompile and
link your clients with the new client library. See section E.2 Debugging a MySQL client.
This section describes some of the issues involved in using MIT-pthreads.
Note that on Linux you should not use MIT-pthreads but install LinuxThreads! See section 2.6.1 Linux Notes (All Linux Versions).
If your system does not provide native thread support, you will need to build MySQL using the MIT-pthreads package. This includes older FreeBSD systems, SunOS 4.x, Solaris 2.4 and earlier, and some others. See section 2.2.5 Operating Systems Supported by MySQL.
Note, that beginning with MySQL 4.0.2 MIT-pthreads are no longer part of the source distribution! If you require this package, you need to download it separately from http://www.mysql.com/Downloads/Contrib/pthreads-1_60_beta6-mysql.tar.gz
After downloading, extract this source archive into the top level of the
MySQL source directory. It will create a new subdirectory
mit-pthreads.
configure with the --with-mit-threads option:
shell> ./configure --with-mit-threadsBuilding in a non-source directory is not supported when using MIT-pthreads because we want to minimise our changes to this code.
--without-server
to build only the client code, clients will not know whether
MIT-pthreads is being used and will use Unix socket connections by default.
Because Unix sockets do not work under MIT-pthreads on some platforms, this
means you will need to use -h or --host when you run client
programs.
--external-locking option. This is only
needed if you want to be able to run two MySQL servers against the same
data files (not recommended).
bind() command fails to bind to a socket without
any error message (at least on Solaris). The result is that all connections
to the server fail. For example:
shell> mysqladmin version mysqladmin: connect to server at '' failed; error: 'Can't connect to mysql server on localhost (146)'The solution to this is to kill the
mysqld server and restart it.
This has only happened to us when we have forced the server down and done
a restart immediately.
sleep() system call isn't interruptible with
SIGINT (break). This is only noticeable when you run
mysqladmin --sleep. You must wait for the sleep() call to
terminate before the interrupt is served and the process stops.
ld: warning: symbol `_iob' has differing sizes:
(file /my/local/pthreads/lib/libpthread.a(findfp.o) value=0x4;
file /usr/lib/libc.so value=0x140);
/my/local/pthreads/lib/libpthread.a(findfp.o) definition taken
ld: warning: symbol `__iob' has differing sizes:
(file /my/local/pthreads/lib/libpthread.a(findfp.o) value=0x4;
file /usr/lib/libc.so value=0x140);
/my/local/pthreads/lib/libpthread.a(findfp.o) definition taken
implicit declaration of function `int strtoll(...)' implicit declaration of function `int strtoul(...)'
readline to work with MIT-pthreads. (This isn't
needed, but may be interesting for someone.)
You will need the following:
Building MySQL
File menu, select Open Workspace.
Build menu,
select the Set Active Configuration menu.
mysqld - Win32 Debug
and click OK.
F7 to begin the build of the debug server, libs, and
some client applications.
Set up and start the server in the same way as for the binary Windows distribution. See section 2.1.2.2 Preparing the Windows MySQL Environment.
Once you've installed MySQL (from either a binary or source distribution), you need to initialise the grant tables, start the server, and make sure that the server works okay. You may also wish to arrange for the server to be started and stopped automatically when your system starts up and shuts down.
Normally you install the grant tables and start the server like this for installation from a source distribution:
shell> ./scripts/mysql_install_db shell> cd mysql_installation_directory shell> ./bin/safe_mysqld --user=mysql &
For a binary distribution (not RPM or pkg packages), do this:
shell> cd mysql_installation_directory shell> ./scripts/mysql_install_db shell> ./bin/safe_mysqld --user=mysql & or shell> ./bin/mysqld_safe --user=mysql & if you are running MySQL 4.x.
This creates the mysql database which will hold all database
privileges, the test database which you can use to test
MySQL, and also privilege entries for the user that run
mysql_install_db and a root user (without any passwords).
This also starts the mysqld server.
mysql_install_db will not overwrite any old privilege tables, so
it should be safe to run in any circumstances. If you don't want to
have the test database you can remove it with mysqladmin -u
root drop test.
Testing is most easily done from the top-level directory of the MySQL distribution. For a binary distribution, this is your installation directory (typically something like `/usr/local/mysql'). For a source distribution, this is the main directory of your MySQL source tree.
In the commands shown in this section and in the following
subsections, BINDIR is the path to the location in which programs
like mysqladmin and safe_mysqld are installed. For a
binary distribution, this is the `bin' directory within the
distribution. For a source distribution, BINDIR is probably
`/usr/local/bin', unless you specified an installation directory
other than `/usr/local' when you ran configure.
EXECDIR is the location in which the mysqld server is
installed. For a binary distribution, this is the same as
BINDIR. For a source distribution, EXECDIR is probably
`/usr/local/libexec'.
Testing is described in detail:
mysqld server and set up the initial
MySQL grant tables containing the privileges that determine how
users are allowed to connect to the server. This is normally done with the
mysql_install_db script:
shell> scripts/mysql_install_dbTypically,
mysql_install_db needs to be run only the first time you
install MySQL. Therefore, if you are upgrading an existing
installation, you can skip this step. (However, mysql_install_db is
quite safe to use and will not update any tables that already exist, so if
you are unsure of what to do, you can always run mysql_install_db.)
mysql_install_db creates six tables (user, db,
host, tables_priv, columns_priv, and func) in the
mysql database. A description of the initial privileges is given in
section 4.3.4 Setting Up the Initial MySQL Privileges. Briefly, these privileges allow the MySQL
root user to do anything, and allow anybody to create or use databases
with a name of test or starting with test_.
If you don't set up the grant tables, the following error will appear in the
log file when you start the server:
mysqld: Can't find file: 'host.frm'This may also happen with a binary MySQL distribution if you don't start MySQL by executing exactly
./bin/safe_mysqld!
See section 4.7.2 safe_mysqld, The Wrapper Around mysqld.
You might need to run mysql_install_db as root. However,
if you prefer, you can run the MySQL server as an unprivileged
(non-root) user, provided that the user can read and write files in
the database directory. Instructions for running MySQL as an
unprivileged user are given in section A.3.2 How to Run MySQL As a Normal User.
If you have problems with mysql_install_db, see
section 2.4.1 Problems Running mysql_install_db.
There are some alternatives to running the mysql_install_db
script as it is provided in the MySQL distribution:
mysql_install_db before running it, to change
the initial privileges that are installed into the grant tables. This is
useful if you want to install MySQL on a lot of machines with the
same privileges. In this case you probably should need only to add a few
extra INSERT statements to the mysql.user and mysql.db
tables!
mysql_install_db, then use mysql -u root mysql to
connect to the grant tables as the MySQL root user and issue
SQL statements to modify the grant tables directly.
mysql_install_db.
shell> cd mysql_installation_directory shell> bin/safe_mysqld &If you have problems starting the server, see section 2.4.2 Problems Starting the MySQL Server.
mysqladmin to verify that the server is running. The following
commands provide a simple test to check that the server is up and responding
to connections:
shell> BINDIR/mysqladmin version shell> BINDIR/mysqladmin variablesThe output from
mysqladmin version varies slightly depending on your
platform and version of MySQL, but should be similar to that shown here:
shell> BINDIR/mysqladmin version mysqladmin Ver 8.14 Distrib 3.23.32, for linux on i586 Copyright (C) 2000 MySQL AB & MySQL Finland AB & TCX DataKonsult AB This software comes with ABSOLUTELY NO WARRANTY. This is free software, and you are welcome to modify and redistribute it under the GPL license. Server version 3.23.32-debug Protocol version 10 Connection Localhost via Unix socket TCP port 3306 UNIX socket /tmp/mysql.sock Uptime: 16 sec Threads: 1 Questions: 9 Slow queries: 0 Opens: 7 Flush tables: 2 Open tables: 0 Queries per second avg: 0.000 Memory in use: 132K Max memory used: 16773KTo get a feeling for what else you can do with
BINDIR/mysqladmin,
invoke it with the --help option.
shell> BINDIR/mysqladmin -u root shutdown
safe_mysqld or
by invoking mysqld directly. For example:
shell> BINDIR/safe_mysqld --log &If
safe_mysqld fails, try running it from the MySQL
installation directory (if you are not already there). If that doesn't work,
see section 2.4.2 Problems Starting the MySQL Server.
shell> BINDIR/mysqlshow +-----------+ | Databases | +-----------+ | mysql | +-----------+ shell> BINDIR/mysqlshow mysql Database: mysql +--------------+ | Tables | +--------------+ | columns_priv | | db | | func | | host | | tables_priv | | user | +--------------+ shell> BINDIR/mysql -e "SELECT host,db,user FROM db" mysql +------+--------+------+ | host | db | user | +------+--------+------+ | % | test | | | % | test_% | | +------+--------+------+There is also a benchmark suite in the `sql-bench' directory (under the MySQL installation directory) that you can use to compare how MySQL performs on different platforms. The `sql-bench/Results' directory contains the results from many runs against different databases and platforms. To run all tests, execute these commands:
shell> cd sql-bench shell> run-all-testsIf you don't have the `sql-bench' directory, you are probably using an RPM for a binary distribution. (Source distribution RPMs include the benchmark directory.) In this case, you must first install the benchmark suite before you can use it. Beginning with MySQL Version 3.22, there are benchmark RPM files named `mysql-bench-VERSION-i386.rpm' that contain benchmark code and data. If you have a source distribution, you can also run the tests in the `tests' subdirectory. For example, to run `auto_increment.tst', do this:
shell> BINDIR/mysql -vvf test < ./tests/auto_increment.tstThe expected results are shown in the `./tests/auto_increment.res' file.
mysql_install_db
The purpose of the mysql_install_db script is to generate new
MySQL privilege tables. It will not affect any other data!
It will also not do anything if you already have MySQL privilege
tables installed!
If you want to re-create your privilege tables, you should take down
the mysqld server, if it's running, and then do something like:
mv mysql-data-directory/mysql mysql-data-directory/mysql-old mysql_install_db
This section lists problems you might encounter when you run
mysql_install_db:
mysql_install_db doesn't install the grant tables
mysql_install_db fails to install the grant
tables and terminates after displaying the following messages:
starting mysqld daemon with databases from XXXXXX mysql daemon endedIn this case, you should examine the log file very carefully! The log should be located in the directory `XXXXXX' named by the error message, and should indicate why
mysqld didn't start. If you don't understand
what happened, include the log when you post a bug report using
mysqlbug!
See section 1.6.1.3 How to Report Bugs or Problems.
mysqld daemon running
mysql_install_db at
all. You have to run mysql_install_db only once, when you install
MySQL the first time.
mysqld daemon doesn't work when one daemon is running
Can't start server: Bind on
TCP/IP port: Address already in use or Can't start server: Bind on
unix socket.... See section 4.1.3 Installing Many Servers on the Same Machine.
mysql_install_db or when
starting or using mysqld.
You can specify a different socket and temporary directory as follows:
shell> TMPDIR=/some_tmp_dir/ shell> MYSQL_UNIX_PORT=/some_tmp_dir/mysqld.sock shell> export TMPDIR MYSQL_UNIX_PORTSee section A.4.5 How to Protect or Change the MySQL Socket File `/tmp/mysql.sock'. `some_tmp_dir' should be the path to some directory for which you have write permission. See section F Environment Variables. After this you should be able to run
mysql_install_db and start
the server with these commands:
shell> scripts/mysql_install_db shell> BINDIR/safe_mysqld &
mysqld crashes immediately
glibc older than
2.0.7-5, you should make sure you have installed all glibc patches!
There is a lot of information about this in the MySQL mail
archives. Links to the mail archives are available online at
http://lists.mysql.com/.
Also, see section 2.6.1 Linux Notes (All Linux Versions).
You can also start mysqld manually using the --skip-grant-tables
option and add the privilege information yourself using mysql:
shell> BINDIR/safe_mysqld --skip-grant-tables & shell> BINDIR/mysql -u root mysqlFrom
mysql, manually execute the SQL commands in
mysql_install_db. Make sure you run mysqladmin
flush-privileges or mysqladmin reload afterward to tell the server to
reload the grant tables.
If you are going to use tables that support transactions (InnoDB, BDB), you should first create a `my.cnf' file and set startup options for the table types you plan to use. See section 7 MySQL Table Types.
Generally, you start the mysqld server in one of these ways:
mysql.server. This script is used primarily at
system startup and shutdown, and is described more fully in
section 2.4.3 Starting and Stopping MySQL Automatically.
safe_mysqld, which tries to determine the proper options
for mysqld and then runs it with those options. See section 4.7.2 safe_mysqld, The Wrapper Around mysqld.
mysqld directly.
When the mysqld daemon starts up, it changes the directory to the
data directory. This is where it expects to write log files and the pid
(process ID) file, and where it expects to find databases.
The data directory location is hardwired in when the distribution is
compiled. However, if mysqld expects to find the data directory
somewhere other than where it really is on your system, it will not work
properly. If you have problems with incorrect paths, you can find out
what options mysqld allows and what the default path settings are by
invoking mysqld with the --help option. You can override the
defaults by specifying the correct pathnames as command-line arguments to
mysqld. (These options can be used with safe_mysqld as well.)
Normally you should need to tell mysqld only the base directory under
which MySQL is installed. You can do this with the --basedir
option. You can also use --help to check the effect of changing path
options (note that --help must be the final option of the
mysqld command). For example:
shell> EXECDIR/mysqld --basedir=/usr/local --help
Once you determine the path settings you want, start the server without
the --help option.
Whichever method you use to start the server, if it fails to start up
correctly, check the log file to see if you can find out why. Log files
are located in the data directory (typically
`/usr/local/mysql/data' for a binary distribution,
`/usr/local/var' for a source distribution, and
`\mysql\data\mysql.err' on Windows). Look in the data directory for
files with names of the form `host_name.err' and
`host_name.log' where host_name is the name of your server
host. Then check the last few lines of these files:
shell> tail host_name.err shell> tail host_name.log
Look for something like the following in the log file:
000729 14:50:10 bdb: Recovery function for LSN 1 27595 failed 000729 14:50:10 bdb: warning: ./test/t1.db: No such file or directory 000729 14:50:10 Can't init databases
This means that you didn't start mysqld with --bdb-no-recover
and Berkeley DB found something wrong with its log files when it
tried to recover your databases. To be able to continue, you should
move away the old Berkeley DB log file from the database directory to
some other place, where you can later examine it. The log files are
named `log.0000000001', where the number will increase over time.
If you are running mysqld with BDB table support and mysqld core
dumps at start this could be because of some problems with the BDB
recover log. In this case you can try starting mysqld with
--bdb-no-recover. If this helps, then you should remove all
`log.*' files from the data directory and try starting mysqld
again.
If you get the following error, it means that some other program (or another
mysqld server) is already using the TCP/IP port or socket
mysqld is trying to use:
Can't start server: Bind on TCP/IP port: Address already in use or Can't start server : Bind on unix socket...
Use ps to make sure that you don't have another mysqld server
running. If you can't find another server running, you can try to execute
the command telnet your-host-name tcp-ip-port-number and press
Enter a couple of times. If you don't get an error message like
telnet: Unable to connect to remote host: Connection refused,
something is using the TCP/IP port mysqld is trying to use.
See section 2.4.1 Problems Running mysql_install_db and section 4.1.4 Running Multiple MySQL Servers on the Same Machine.
If mysqld is currently running, you can find out what path settings
it is using by executing this command:
shell> mysqladmin variables
or
shell> mysqladmin -h 'your-host-name' variables
If you get Errcode 13, which means Permission denied, when
starting mysqld this means that you didn't have the right to
read/create files in the MySQL database or log directory. In this case
you should either start mysqld as the root user or change the
permissions for the involved files and directories so that you have the
right to use them.
If safe_mysqld starts the server but you can't connect to it,
you should make sure you have an entry in `/etc/hosts' that looks like
this:
127.0.0.1 localhost
This problem occurs only on systems that don't have a working thread library and for which MySQL must be configured to use MIT-pthreads.
If you can't get mysqld to start you can try to make a trace file
to find the problem. See section E.1.2 Creating Trace Files.
If you are using InnoDB tables, refer to the InnoDB-specific startup options. See section 7.5.2 InnoDB Startup Options.
If you are using BDB (Berkeley DB) tables, you should familiarise
yourself with the different BDB-specific startup options. See section 7.6.3 BDB startup options.
The mysql.server and safe_mysqld scripts can be used to start
the server automatically at system startup time. mysql.server can also
be used to stop the server.
The mysql.server script can be used to start or stop the server
by invoking it with start or stop arguments:
shell> mysql.server start shell> mysql.server stop
mysql.server can be found in the `share/mysql' directory
under the MySQL installation directory or in the `support-files'
directory of the MySQL source tree.
Before mysql.server starts the server, it changes the directory to
the MySQL installation directory, then invokes safe_mysqld.
You might need to edit mysql.server if you have a binary distribution
that you've installed in a non-standard location. Modify it to cd
into the proper directory before it runs safe_mysqld. If you want the
server to run as some specific user, add an appropriate user line
to the `/etc/my.cnf' file, as shown later in this section.
mysql.server stop brings down the server by sending a signal to it.
You can also take down the server manually by executing
mysqladmin shutdown.
You need to add these start and stop commands to the appropriate places in your `/etc/rc*' files when you want to start up MySQL automatically on your server.
On most current Linux distributions, it is sufficient to copy the file
mysql.server into the `/etc/init.d' directory (or
`/etc/rc.d/init.d' on older Red Hat systems). Afterwards, run the
following command to enable the startup of MySQL on system bootup:
shell> chkconfig --add mysql.server
As an alternative to the above, some operating systems also use `/etc/rc.local' or `/etc/init.d/boot.local' to start additional services on bootup. To start up MySQL using this method, you could append something like the following to it:
/bin/sh -c 'cd /usr/local/mysql ; ./bin/safe_mysqld --user=mysql &'
You can also add options for mysql.server in a global
`/etc/my.cnf' file. A typical `/etc/my.cnf' file might look like
this:
[mysqld] datadir=/usr/local/mysql/var socket=/var/tmp/mysql.sock port=3306 user=mysql [mysql_server] basedir=/usr/local/mysql
The mysql.server script understands the following options:
datadir, basedir, and pid-file.
The following table shows which option groups each of the startup scripts read from option files:
| Script | Option groups |
mysqld | mysqld and server
|
mysql.server | mysql.server, mysqld, and server
|
safe_mysqld | mysql.server, mysqld, and server
|
See section 4.1.2 `my.cnf' Option Files.
You can always move the MySQL form and datafiles between
different versions on the same architecture as long as you have the same
base version of MySQL. The current base version is
3. If you change the character set when running MySQL (which may
also change the sort order), you must run myisamchk -r -q
--set-character-set=charset on all
tables. Otherwise, your indexes may not be ordered correctly.
If you are afraid of new versions, you can always rename your old
mysqld to something like mysqld-old-version-number. If
your new mysqld then does something unexpected, you can simply shut it
down and restart with your old mysqld!
When you do an upgrade you should also back up your old databases, of course.
If after an upgrade, you experience problems with recompiled client programs,
like Commands out of sync or unexpected core dumps, you probably have
used an old header or library file when compiling your programs. In this
case you should check the date for your `mysql.h' file and
`libmysqlclient.a' library to verify that they are from the new
MySQL distribution. If not, please recompile your programs!
If you get some problems that the new mysqld server doesn't want to
start or that you can't connect without a password, check that you don't
have some old `my.cnf' file from your old installation! You can
check this with: program-name --print-defaults. If this outputs
anything other than the program name, you have an active `my.cnf'
file that will affect things!
It is a good idea to rebuild and reinstall the Msql-Mysql-modules
distribution whenever you install a new release of MySQL,
particularly if you notice symptoms such as all your DBI scripts
dumping core after you upgrade MySQL.
In general what you have to do when upgrading to 4.1 from an earlier MySQL version:
mysql_fix_privilege_tables to generate the new
password field that is needed for secure handling of passwords.
The following is a more complete lists tell what you have to watch out for when upgrading to version 4.1;
mysql> SELECT cast("2001-1-1" as DATE)
-> '2001-01-01'
SHOW CREATE TABLE and mysqldump.
(MySQL 4.0.6 and above can read the new dump files, but not previous
MySQL versions).
'YYYY-MM-DD HH:MM:DD'.
If you want to have this as a number you should add +0 to the timestamp
column. Different timestamp lengths are not supported.
--shared_memory_base_name option on all machines.
Note that the table definition format (.frm) has changed
slightly in 4.1. MySQL 4.0.11 can read the new .frm format but older
version can not. If you need to go move tables from 4.1 to and earlier
MySQL version you should use mysqldump. See section 4.8.5 mysqldump, Dumping Table Structure and Data.
In general what you have to do when upgrading to 4.0 from an earlier MySQL version:
mysql_fix_privilege_tables to add new
privileges and features
to the MySQL privilege tables.
mysql_convert_table_format database. Note that this should only
be run if all tables in the given database is ISAM or MyISAM tables. If
this is not the case you should run ALTER TABLE table_name TYPE=MyISAM
on all ISAM tables.
MySQL 4.0 will work even if you don't do the above, but you will not be able to use the new security privileges that MySQL 4.0 and you may run into problems when upgrading later to MySQL 4.1 or newer. The ISAM file format still works in MySQL 4.0 but it's deprecated and will be disabled in MySQL 5.0.
Old clients should work with a Version 4.0 server without any problems.
Even if you do the above, you can still downgrade to MySQL 3.23.52 or
newer if you run into problems with the MySQL 4.0 series. In this case
you have to do a mysqldump of any tables using a full-text index
and restore these in 3.23 (because 4.0 uses a new format for full-text
index).
The following is a more complete lists tell what you have to watch out for when upgrading to version 4.0;
mysql.user table.
See section 4.3.1 GRANT and REVOKE Syntax.
To get these new privileges to work, one must run the
mysql_fix_privilege_tables script. Until this script is run all
users have the SHOW DATABASES, CREATE TEMPORARY TABLES,
and LOCK TABLES privileges. SUPER and EXECUTE
privileges take their value from PROCESS.
REPLICATION SLAVE and REPLICATION CLIENT take their
values from FILE.
If you have any scripts that creates new users, you may want to change
them to use the new privileges. If you are not using GRANT
commands in the scripts, this is a good time to change your scripts.
In version 4.0.2 the option --safe-show-database is deprecated
(and no longer does anything). See section 4.2.3 Startup Options for mysqld Concerning Security.
If you get access denied errors for new users in version 4.0.2, you
should check if you need some of the new grants that you didn't need
before. In particular, you will need REPLICATION SLAVE
(instead of FILE) for new slaves.
myisam_max_extra_sort_file_size and
myisam_max_extra_sort_file_size are now given in bytes
(was megabytes before 4.0.3).
External system locking of MyISAM/ISAM files is now turned off by default.
One can turn this on by doing --external-locking. (For most users
this is never needed).
| From | to. |
myisam_bulk_insert_tree_size | bulk_insert_buffer_size
|
query_cache_startup_type | query_cache_type
|
record_buffer | read_buffer_size
|
record_rnd_buffer | read_rnd_buffer_size
|
sort_buffer | sort_buffer_size
|
warnings | log-warnings
|
err-log | --log-error (for mysqld_safe)
|
record_buffer, sort_buffer and
warnings will still work in MySQL 4.0 but are deprecated.
| From | To. |
SQL_BIG_TABLES | BIG_TABLES
|
SQL_LOW_PRIORITY_UPDATES | LOW_PRIORITY_UPDATES
|
SQL_MAX_JOIN_SIZE | MAX_JOIN_SIZE
|
SQL_QUERY_CACHE_TYPE | QUERY_CACHE_TYPE
|
SET GLOBAL SQL_SLAVE_SKIP_COUNTER=# instead of
SET SQL_SLAVE_SKIP_COUNTER=#.
--skip-locking to
--skip-external-locking and --enable-locking to
--external-locking.
SHOW MASTER STATUS now returns an empty set if binary log is not
enabled.
SHOW SLAVE STATUS now returns an empty set if slave is not initialised.
--temp-pool enabled by default as this
gives better performance with some OS (Most notable Linux).
DOUBLE and FLOAT columns now honour the
UNSIGNED flag on storage (before, UNSIGNED was ignored for
these columns).
ORDER BY column DESC now always sorts NULL values
first; in 3.23 this was not always consistent. Note: MySQL 4.0.11 restored
the original behaviour.
SHOW INDEX has 2 columns more (Null and Index_type)
than it had in 3.23.
CHECK, SIGNED, LOCALTIME and LOCALTIMESTAMP
are now reserved words.
|, &, <<,
>>, and ~ is now unsigned. This may cause problems if you
are using them in a context where you want a signed result.
See section 6.3.5 Cast Functions.
UNSIGNED, the result will be unsigned! In other
words, before upgrading to MySQL 4.0, you should check your application
for cases where you are subtracting a value from an unsigned entity and
want a negative answer or subtracting an unsigned value from an
integer column. You can disable this behaviour by using the
--sql-mode=NO_UNSIGNED_SUBTRACTION option when starting
mysqld. See section 6.3.5 Cast Functions.
MATCH ... AGAINST (... IN BOOLEAN MODE) with your tables,
you need to rebuild them with REPAIR TABLE table_name USE_FRM.
LOCATE() and INSTR() are case-sensitive if one of the
arguments is a binary string. Otherwise they are case-insensitive.
STRCMP() now uses the current character set when doing comparisons,
which means that the default comparison behaviour now is case-insensitive.
HEX(string) now returns the characters in string converted to
hexadecimal. If you want to convert a number to hexadecimal, you should
ensure that you call HEX() with a numeric argument.
INSERT INTO ... SELECT always had IGNORE enabled.
In 4.0.1, MySQL will stop (and possibly roll back) in case of an error if you
don't specify IGNORE.
safe_mysqld as a symlink to
mysqld_safe.
mysql_drop_db, mysql_create_db, and
mysql_connect are not supported anymore, unless you compile
MySQL with CFLAGS=-DUSE_OLD_FUNCTIONS. Instead of doing this,
it is preferable to change the client to use the new 4.0 API.
MYSQL_FIELD structure, length and max_length have
changed from unsigned int to unsigned long. This should not
cause any problems, except that they may generate warning messages when
used as arguments in the printf() class of functions.
TRUNCATE TABLE when you want to delete all rows
from a table and you don't care how many rows were deleted.
(Because TRUNCATE TABLE is faster than DELETE FROM table_name).
LOCK TABLES or
transaction when trying to execute TRUNCATE TABLE or DROP
DATABASE.
SHOW OPEN TABLE has changed.
mysql_thread_init() and
mysql_thread_end(). See section 8.4.8 How to Make a Threaded Client.
drop_db() call.
RAND(seed) returns a different random number series in 4.0 than in
3.23; this was done to further differentiate RAND(seed) and
RAND(seed+1).
IFNULL(A,B) is now set to be the
more 'general' of the types of A and B. (The order is
STRING, REAL or INTEGER).
MySQL Version 3.23 supports tables of the new MyISAM type and
the old ISAM type. You don't have to convert your old tables to
use these with Version 3.23. By default, all new tables will be created with
type MyISAM (unless you start mysqld with the
--default-table-type=isam option). You can change an ISAM
table to a MyISAM table with ALTER TABLE table_name TYPE=MyISAM
or the Perl script mysql_convert_table_format.
Version 3.22 and 3.21 clients will work without any problems with a Version 3.23 server.
The following list tells what you have to watch out for when upgrading to Version 3.23:
tis620 character set must be fixed
with myisamchk -r or REPAIR TABLE.
DROP DATABASE on a symbolic linked database, both the
link and the original database are deleted. (This didn't happen in 3.22
because configure didn't detect the readlink system call.)
OPTIMIZE TABLE now works only for MyISAM tables.
For other table types, you can use ALTER TABLE to optimise the table.
During OPTIMIZE TABLE the table is now locked from other threads.
mysql is now by default started with the
option --no-named-commands (-g). This option can be disabled with
--enable-named-commands (-G). This may cause incompatibility problems in
some cases@-for example, in SQL scripts that use named commands without a
semicolon! Long format commands still work from the first line.
MONTH()) will now
return 0 for 0000-00-00 dates. (MySQL 3.22 returned NULL.)
german character sort order, you must repair
all your tables with isamchk -r, as we have made some changes in
the sort order!
IF will now depend on both arguments
and not only the first argument.
AUTO_INCREMENT will not work with negative numbers. The reason
for this is that negative numbers caused problems when wrapping from -1 to 0.
AUTO_INCREMENT for MyISAM tables is now handled at a lower level and
is much faster than before. For MyISAM tables old numbers are also not reused
anymore, even if you delete some rows from the table.
CASE, DELAYED, ELSE, END, FULLTEXT,
INNER, RIGHT, THEN, and WHEN are now reserved words.
FLOAT(X) is now a true floating-point type and not a value with a
fixed number of decimals.
DECIMAL(length,dec) the length argument no longer
includes a place for the sign or the decimal point.
TIME string must now be of one of the following formats:
[[[DAYS] [H]H:]MM:]SS[.fraction] or
[[[[[H]H]H]H]MM]SS[.fraction].
LIKE now compares strings using the same character comparison rules
as =. If you require the old behaviour, you can compile
MySQL with the CXXFLAGS=-DLIKE_CMP_TOUPPER flag.
REGEXP is now case-insensitive for normal (not binary) strings.
CHECK TABLE
or myisamchk for MyISAM tables (`.MYI') and
isamchk for ISAM (`.ISM') tables.
mysqldump files to be compatible between
MySQL Version 3.22 and Version 3.23, you should not use the
--opt or --all option to mysqldump.
DATE_FORMAT() to make sure there is a
`%' before each format character.
(MySQL Version 3.22 and later already allowed this syntax.)
mysql_fetch_fields_direct is now a function (it was a macro) and
it returns a pointer to a MYSQL_FIELD instead of a
MYSQL_FIELD.
mysql_num_fields() can no longer be used on a MYSQL* object (it's
now a function that takes MYSQL_RES* as an argument, so you should
use mysql_field_count() instead).
SELECT DISTINCT ... was
almost always sorted. In Version 3.23, you must use GROUP BY or
ORDER BY to obtain sorted output.
SUM() now returns NULL, instead of 0, if
there are no matching rows. This is according to ANSI SQL.
AND or OR with NULL values will now return
NULL instead of 0. This mostly affects queries that use NOT
on an AND/OR expression as NOT NULL = NULL.
LPAD() and RPAD() will shorten the result string if it's longer
than the length argument.
Nothing that affects compatibility has changed between versions 3.21 and 3.22.
The only pitfall is that new tables that are created with DATE type
columns will use the new way to store the date. You can't access these new
fields from an old version of mysqld.
After installing MySQL Version 3.22, you should start the new server
and then run the mysql_fix_privilege_tables script. This will add the
new privileges that you need to use the GRANT command. If you forget
this, you will get Access denied when you try to use ALTER
TABLE, CREATE INDEX, or DROP INDEX. If your MySQL root
user requires a password, you should give this as an argument to
mysql_fix_privilege_tables.
The C API interface to mysql_real_connect() has changed. If you have
an old client program that calls this function, you must place a 0 for
the new db argument (or recode the client to send the db
element for faster connections). You must also call mysql_init()
before calling mysql_real_connect()! This change was done to allow
the new mysql_options() function to save options in the MYSQL
handler structure.
The mysqld variable key_buffer has changed names to
key_buffer_size, but you can still use the old name in your
startup files.
If you are running a version older than Version 3.20.28 and want to switch to Version 3.21, you need to do the following:
You can start the mysqld Version 3.21 server with safe_mysqld
--old-protocol to use it with clients from a Version 3.20 distribution.
In this case, the new client function mysql_errno() will not
return any server error, only CR_UNKNOWN_ERROR (but it
works for client errors), and the server uses the old password()
checking rather than the new one.
If you are not using the --old-protocol option to
mysqld, you will need to make the following changes:
MyODBC 2.x driver.
scripts/add_long_password must be run to convert the
Password field in the mysql.user table to CHAR(16).
mysql.user table (to get 62-bit
rather than 31-bit passwords).
MySQL Version 3.20.28 and above can handle the new user table
format without affecting clients. If you have a MySQL version earlier
than Version 3.20.28, passwords will no longer work with it if you convert the
user table. So to be safe, you should first upgrade to at least Version
3.20.28 and then upgrade to Version 3.21.
The new client code works with a 3.20.x mysqld server, so
if you experience problems with 3.21.x, you can use the old 3.20.x server
without having to recompile the clients again.
If you are not using the --old-protocol option to mysqld,
old clients will issue the error message:
ERROR: Protocol mismatch. Server Version = 10 Client Version = 9
The new Perl DBI/DBD interface also supports the old
mysqlperl interface. The only change you have to make if you use
mysqlperl is to change the arguments to the connect() function.
The new arguments are: host, database, user,
and password (the user and password arguments have changed
places).
See section 8.2.2 The DBI Interface.
The following changes may affect queries in old applications:
HAVING must now be specified before any ORDER BY clause.
LOCATE() have been swapped.
DATE,
TIME, and TIMESTAMP.
If you are using MySQL Version 3.23, you can copy the `.frm', `.MYI', and `.MYD' files between different architectures that support the same floating-point format. (MySQL takes care of any byte-swapping issues.)
The MySQL ISAM data and index files (`.ISD' and
`*.ISM', respectively) are architecture-dependent and in some cases
OS-dependent. If you want to move your applications to another machine
that has a different architecture or OS than your current machine, you
should not try to move a database by simply copying the files to the
other machine. Use mysqldump instead.
By default, mysqldump will create a file full of SQL statements.
You can then transfer the file to the other machine and feed it as input
to the mysql client.
Try mysqldump --help to see what options are available.
If you are moving the data to a newer version of MySQL, you should use
mysqldump --opt with the newer version to get a fast, compact dump.
The easiest (although not the fastest) way to move a database between two machines is to run the following commands on the machine on which the database is located:
shell> mysqladmin -h 'other hostname' create db_name
shell> mysqldump --opt db_name \
| mysql -h 'other hostname' db_name
If you want to copy a database from a remote machine over a slow network, you can use:
shell> mysqladmin create db_name
shell> mysqldump -h 'other hostname' --opt --compress db_name \
| mysql db_name
You can also store the result in a file, then transfer the file to the target machine and load the file into the database there. For example, you can dump a database to a file on the source machine like this:
shell> mysqldump --quick db_name | gzip > db_name.contents.gz
(The file created in this example is compressed.) Transfer the file containing the database contents to the target machine and run these commands there:
shell> mysqladmin create db_name shell> gunzip < db_name.contents.gz | mysql db_name
You can also use mysqldump and mysqlimport to accomplish
the database transfer.
For big tables, this is much faster than simply using mysqldump.
In the following commands, DUMPDIR represents the full pathname
of the directory you use to store the output from mysqldump.
First, create the directory for the output files and dump the database:
shell> mkdir DUMPDIR shell> mysqldump --tab=DUMPDIR db_name
Then transfer the files in the DUMPDIR directory to some corresponding
directory on the target machine and load the files into MySQL
there:
shell> mysqladmin create db_name # create database shell> cat DUMPDIR/*.sql | mysql db_name # create tables in database shell> mysqlimport db_name DUMPDIR/*.txt # load data into tables
Also, don't forget to copy the mysql database because that's where the
grant tables (user, db, host) are stored. You may have
to run commands as the MySQL root user on the new machine
until you have the mysql database in place.
After you import the mysql database on the new machine, execute
mysqladmin flush-privileges so that the server reloads the grant table
information.
The following notes regarding glibc apply only to the situation
when you build MySQL
yourself. If you are running Linux on an x86 machine, in most cases it is
much better for you to just use our binary. We link our binaries against
the best patched version of glibc we can come up with and with the
best compiler options, in an attempt to make it suitable for a high-load
server. So if you read the following text, and are in doubt about
what you should do, try our binary first to see if it meets your needs, and
worry about your own build only after you have discovered that our binary is
not good enough. In that case, we would appreciate a note about it, so we
can build a better binary next time. For a typical user, even for setups with
a lot of concurrent connections and/or tables exceeding the 2G limit, our
binary in most cases is the best choice.
MySQL uses LinuxThreads on Linux. If you are using an old
Linux version that doesn't have glibc2, you must install
LinuxThreads before trying to compile MySQL. You can get
LinuxThreads at http://www.mysql.com/downloads/os-linux.html.
Note: we have seen some strange problems with Linux 2.2.14 and MySQL on SMP systems. If you have a SMP system, we recommend you upgrade to Linux 2.4 as soon as possible! Your system will be faster and more stable by doing this!
Note that glibc versions before and including Version 2.1.1 have
a fatal bug in pthread_mutex_timedwait handling, which is used
when you do INSERT DELAYED. We recommend that you not use
INSERT DELAYED before upgrading glibc.
If you plan to have 1000+ concurrent connections, you will need to make
some changes to LinuxThreads, recompile it, and relink MySQL against
the new `libpthread.a'. Increase PTHREAD_THREADS_MAX in
`sysdeps/unix/sysv/linux/bits/local_lim.h' to 4096 and decrease
STACK_SIZE in `linuxthreads/internals.h' to 256 KB. The paths are
relative to the root of glibc Note that MySQL will not be
stable with around 600-1000 connections if STACK_SIZE is the default
of 2 MB.
If MySQL can't open enough files, or connections, it may be that you haven't configured Linux to handle enough files.
In Linux 2.2 and onward, you can check the number of allocated file handles by doing:
cat /proc/sys/fs/file-max cat /proc/sys/fs/dquot-max cat /proc/sys/fs/super-max
If you have more than 16 MB of memory, you should add something like the following to your init scripts (e.g. `/etc/init.d/boot.local' on SuSE Linux):
echo 65536 > /proc/sys/fs/file-max echo 8192 > /proc/sys/fs/dquot-max echo 1024 > /proc/sys/fs/super-max
You can also run the preceding commands from the command-line as root, but these settings will be lost the next time your computer reboots.
Alternatively, you can set these parameters on bootup by using the
sysctl tool, which is used by many Linux distributions (SuSE has
added it as well, beginning with SuSE Linux 8.0). Just put the following
values into a file named `/etc/sysctl.conf':
# Increase some values for MySQL fs.file-max = 65536 fs.dquot-max = 8192 fs.super-max = 1024
You should also add the following to `/etc/my.cnf':
[safe_mysqld] open-files-limit=8192
This should allow MySQL to create up to 8192 connections + files.
The STACK_SIZE constant in LinuxThreads controls the spacing of thread
stacks in the address space. It needs to be large enough so that there will
be plenty of room for the stack of each individual thread, but small enough
to keep the stack of some threads from running into the global mysqld
data. Unfortunately, the Linux implementation of mmap(), as we have
experimentally discovered, will successfully unmap an already mapped region
if you ask it to map out an address already in use, zeroing out the data
on the entire page, instead of returning an error. So, the safety of
mysqld or any other threaded application depends on the "gentleman"
behaviour of the code that creates threads. The user must take measures to
make sure the number of running threads at any time is sufficiently low for
thread stacks to stay away from the global heap. With mysqld, you
should enforce this "gentleman" behaviour by setting a reasonable value for
the max_connections variable.
If you build MySQL yourself and do not want to mess with patching
LinuxThreads, you should set max_connections to a value no higher
than 500. It should be even less if you have a large key buffer, large
heap tables, or some other things that make mysqld allocate a lot
of memory, or if you are running a 2.2 kernel with a 2G patch. If you are
using our binary or RPM version 3.23.25 or later, you can safely set
max_connections at 1500, assuming no large key buffer or heap tables
with lots of data. The more you reduce STACK_SIZE in LinuxThreads
the more threads you can safely create. We recommend the values between
128K and 256K.
If you use a lot of concurrent connections, you may suffer from a "feature"
in the 2.2 kernel that penalises a process for forking or cloning a child
in an attempt to prevent a fork bomb attack. This will cause MySQL
not to scale well as you increase the number of concurrent clients. On
single-CPU systems, we have seen this manifested in a very slow thread
creation, which means it may take a long time to connect to MySQL
(as long as 1 minute), and it may take just as long to shut it down. On
multiple-CPU systems, we have observed a gradual drop in query speed as
the number of clients increases. In the process of trying to find a
solution, we have received a kernel patch from one of our users, who
claimed it made a lot of difference for his site. The patch is available at
http://www.mysql.com/Downloads/Patches/linux-fork.patch. We have
now done rather extensive testing of this patch on both development and
production systems. It has significantly
improved MySQL performance without causing any problems and we now
recommend it to our users who are still running high-load servers on
2.2 kernels. This issue has been fixed in the 2.4 kernel, so if you are not
satisfied with
the current performance of your system, rather than patching your 2.2 kernel,
it might be easier to just upgrade to 2.4, which will also give you a nice
SMP boost in addition to fixing this fairness bug.
We have tested MySQL on the 2.4 kernel on a 2-CPU machine and
found MySQL scales much better@-there was virtually no slowdown
on queries throughput all the way up
to 1000 clients, and the MySQL scaling factor (computed as the ratio of
maximum throughput to the throughput with one client) was 180%.
We have observed similar results on a 4-CPU system@-virtually no
slowdown as the number of
clients was increased up to 1000, and 300% scaling factor. So for a high-load
SMP server we would definitely recommend the 2.4 kernel at this point. We
have discovered that it is essential to run mysqld process with the
highest possible priority on the 2.4 kernel to achieve maximum performance.
This can be done by adding
renice -20 $$ command to safe_mysqld. In our testing on a
4-CPU machine, increasing the priority gave 60% increase in throughput with
400 clients.
We are currently also trying to collect
more info on how well MySQL performs on 2.4 kernel on 4-way and 8-way
systems. If you have access such a system and have done some benchmarks,
please send a mail to docs@mysql.com with the results - we will
include them in the manual.
There is another issue that greatly hurts MySQL performance,
especially on SMP systems. The implementation of mutex in
LinuxThreads in glibc-2.1 is very bad for programs with many
threads that only
hold the mutex for a short time. On an SMP system, ironic as it is, if
you link MySQL against unmodified LinuxThreads,
removing processors from the machine improves MySQL performance
in many cases. We have made a patch available for glibc 2.1.3
to correct this behaviour
(http://www.mysql.com/Downloads/Linux/linuxthreads-2.1-patch).
With glibc-2.2.2
MySQL version 3.23.36 will use the adaptive mutex, which is much
better than even the patched one in glibc-2.1.3. Be warned, however,
that under some conditions, the current mutex code in glibc-2.2.2
overspins, which hurts MySQL performance. The chance of this
condition can be reduced by renicing mysqld process to the highest
priority. We have also been able to correct the overspin behaviour with
a patch, available at
http://www.mysql.com/Downloads/Linux/linuxthreads-2.2.2.patch.
It combines the correction of overspin, maximum number of
threads, and stack spacing all in one. You will need to apply it in the
linuxthreads directory with
patch -p0 </tmp/linuxthreads-2.2.2.patch.
We hope it will be included in
some form in to the future releases of glibc-2.2. In any case, if
you link against glibc-2.2.2 you still need to correct
STACK_SIZE and PTHREAD_THREADS_MAX. We hope that the defaults
will be corrected to some more acceptable values for high-load
MySQL setup in the future, so that your own build can be reduced
to ./configure; make; make install.
We recommend that you use the above patches to build a special static
version of libpthread.a and use it only for statically linking
against MySQL. We know that the patches are safe for MySQL
and significantly improve its performance, but we cannot say anything
about other applications. If you link other applications against the
patched version of the library, or build a patched shared version and
install it on your system, you are doing it at your own risk with regard
to other applications that depend on LinuxThreads.
If you experience any strange problems during the installation of MySQL, or with some common utilties hanging, it is very likely that they are either library or compiler related. If this is the case, using our binary will resolve them.
One known problem with the binary distribution is that with older Linux
systems that use libc (like RedHat 4.x or Slackware), you will get
some non-fatal problems with hostname resolution.
See section 2.6.1.1 Linux Notes for Binary Distributions.
When using LinuxThreads you will see a minimum of three processes running. These are in fact threads. There will be one thread for the LinuxThreads manager, one thread to handle connections, and one thread to handle alarms and signals.
Note that the Linux kernel and the LinuxThread library can by default only have 1024 threads. This means that you can only have up to 1021 connections to MySQL on an unpatched system. The page http://www.volano.com/linuxnotes.html contains information how to go around this limit.
If you see a dead mysqld daemon process with ps, this usually
means that you have found a bug in MySQL or you have a corrupted
table. See section A.4.1 What To Do If MySQL Keeps Crashing.
To get a core dump on Linux if mysqld dies with a SIGSEGV signal,
you can start mysqld with the --core-file option. Note
that you also probably need to raise the core file size by adding
ulimit -c 1000000 to safe_mysqld or starting
safe_mysqld with --core-file-size=1000000.
See section 4.7.2 safe_mysqld, The Wrapper Around mysqld.
If you are linking your own MySQL client and get the error:
ld.so.1: ./my: fatal: libmysqlclient.so.4: open failed: No such file or directory
When executing them, the problem can be avoided by one of the following methods:
-Lpath):
-Wl,r/path-libmysqlclient.so.
libmysqclient.so to `/usr/lib'.
LD_RUN_PATH environment variable before running your client.
If you are using the Fujitsu compiler (fcc / FCC) you will have
some problems compiling MySQL because the Linux header files are very
gcc oriented.
The following configure line should work with fcc/FCC:
CC=fcc CFLAGS="-O -K fast -K lib -K omitfp -Kpreex -D_GNU_SOURCE \ -DCONST=const -DNO_STRTOLL_PROTO" CXX=FCC CXXFLAGS="-O -K fast -K lib \ -K omitfp -K preex --no_exceptions --no_rtti -D_GNU_SOURCE -DCONST=const \ -Dalloca=__builtin_alloca -DNO_STRTOLL_PROTO \ '-D_EXTERN_INLINE=static __inline'" ./configure --prefix=/usr/local/mysql \ --enable-assembler --with-mysqld-ldflags=-all-static --disable-shared \ --with-low-memory
MySQL needs at least Linux Version 2.0.
Warning: We have reports from some MySQL users that they have got serious stability problems with MySQL with Linux kernel 2.2.14. If you are using this kernel you should upgrade to 2.2.19 (or newer) or to a 2.4 kernel. If you have a multi-cpu box, then you should seriously consider using 2.4 as this will give you a significant speed boost.
The binary release is linked with -static, which means you do not
normally need to worry about which version of the system libraries you
have. You need not install LinuxThreads, either. A program linked with
-static is slightly bigger than a dynamically linked program but
also slightly faster (3-5%). One problem, however, is that you can't use
user-definable functions (UDFs) with a statically linked program. If
you are going to write or use UDF functions (this is something only for
C or C++ programmers), you must compile MySQL yourself, using
dynamic linking.
If you are using a libc-based system (instead of a glibc2
system), you will probably get some problems with hostname resolving and
getpwnam() with the binary release. (This is because glibc
unfortunately depends on some external libraries to resolve hostnames
and getpwent(), even when compiled with -static). In this
case you probably get the following error message when you run
mysql_install_db:
Sorry, the host 'xxxx' could not be looked up
or the following error when you try to run mysqld with the --user
option:
getpwnam: No such file or directory
You can solve this problem in one of the following ways:
tar.gz
distribution) and install this instead.
mysql_install_db --force; this will not execute the
resolveip test in mysql_install_db. The downside is that
you can't use host names in the grant tables; you must use IP numbers
instead (except for localhost). If you are using an old MySQL
release that doesn't support --force, you have to remove the
resolveip test in mysql_install with an editor.
mysqld with su instead of using --user.
The Linux-Intel binary and RPM releases of MySQL are configured for the highest possible speed. We are always trying to use the fastest stable compiler available.
MySQL Perl support requires Version Perl 5.004_03 or newer.
On some Linux 2.2 versions, you may get the error Resource
temporarily unavailable when you do a lot of new connections to a
mysqld server over TCP/IP.
The problem is that Linux has a delay between when you close a TCP/IP socket and until this is actually freed by the system. As there is only room for a finite number of TCP/IP slots, you will get the above error if you try to do too many new TCP/IP connections during a small time, like when you run the MySQL `test-connect' benchmark over TCP/IP.
We have mailed about this problem a couple of times to different Linux mailing lists but have never been able to resolve this properly.
The only known 'fix' to this problem is to use persistent connections in
your clients or use sockets, if you are running the database server
and clients on the same machine. We hope that the Linux 2.4
kernel will fix this problem in the future.
MySQL requires libc Version 5.4.12 or newer. It's known to
work with libc 5.4.46. glibc Version 2.0.6 and later should
also work. There have been some problems with the glibc RPMs from
RedHat, so if you have problems, check whether there are any updates!
The glibc 2.0.7-19 and 2.0.7-29 RPMs are known to work.
If you are using Red Hat 8.0 or a new glibc 2.2.x library you should start
mysqld with the option --thread-stack=192K. If you don't do it
mysqld will die in gethostbyaddr() because the new glibc library
requires > 128K memory on stack for this call. This stack size is now the
default on MySQL 4.0.10 and above.
If you are using gcc 3.0 and above to compile MySQL, you must install
the libstdc++v3 library before compiling MySQL; if you don't do
this you will get an error about a missing __cxa_pure_virtual
symbol during linking!
On some older Linux distributions, configure may produce an error
like this:
Syntax error in sched.h. Change _P to __P in the /usr/include/sched.h file. See the Installation chapter in the Reference Manual.
Just do what the error message says and add an extra underscore to the
_P macro that has only one underscore, then try again.
You may get some warnings when compiling; those shown here can be ignored:
mysqld.cc -o objs-thread/mysqld.o mysqld.cc: In function `void init_signals()': mysqld.cc:315: warning: assignment of negative value `-1' to `long unsigned int' mysqld.cc: In function `void * signal_hand(void *)': mysqld.cc:346: warning: assignment of negative value `-1' to `long unsigned int'
mysql.server can be found in the `share/mysql' directory
under the MySQL installation directory or in the
`support-files' directory of the MySQL source tree.
If mysqld always core dumps when it starts up, the problem may be that
you have an old `/lib/libc.a'. Try renaming it, then remove
`sql/mysqld' and do a new make install and try again. This
problem has been reported on some Slackware installations.
If you get the following error when linking mysqld,
it means that your `libg++.a' is not installed correctly:
/usr/lib/libc.a(putc.o): In function `_IO_putc': putc.o(.text+0x0): multiple definition of `_IO_putc'
You can avoid using `libg++.a' by running configure like this:
shell> CXX=gcc ./configure
In some implementations, readdir_r() is broken. The symptom is that
SHOW DATABASES always returns an empty set. This can be fixed by
removing HAVE_READDIR_R from `config.h' after configuring and
before compiling.
Some problems will require patching your Linux installation. The patch can
be found at
http://www.mysql.com/Downloads/patches/Linux-sparc-2.0.30.diff.
This patch is against the Linux distribution `sparclinux-2.0.30.tar.gz'
that is available at vger.rutgers.edu (a version of Linux that was
never merged with the official 2.0.30). You must also install LinuxThreads
Version 0.6 or newer.
MySQL Version 3.23.12 is the first MySQL version that is tested on Linux-Alpha. If you plan to use MySQL on Linux-Alpha, you should ensure that you have this version or newer.
We have tested MySQL on Alpha with our benchmarks and test suite, and it appears to work nicely.
We currently build the MySQL binary packages on SuSE Linux 7.0 for AXP, kernel 2.4.4-SMP, Compaq C compiler (V6.2-505) and Compaq C++ compiler (V6.3-006) on a Compaq DS20 machine with an Alpha EV6 processor.
You can find the above compilers at http://www.support.compaq.com/alpha-tools/). By using these compilers, instead of gcc, we get about 9-14% better performance with MySQL.
Note that until MySQL version 3.23.52 and 4.0.2 we optimised the binary for
the current CPU only (by using the -fast compile option); this meant
that you could only use our binaries if you had an Alpha EV6 processor.
Starting with all following releases we added the -arch generic flag
to our compile options, which makes sure the binary runs on all Alpha
processors. We also compile statically to avoid library problems.
CC=ccc CFLAGS="-fast -arch generic" CXX=cxx \ CXXFLAGS="-fast -arch generic -noexceptions -nortti" \ ./configure --prefix=/usr/local/mysql --disable-shared \ --with-extra-charsets=complex --enable-thread-safe-client \ --with-mysqld-ldflags=-non_shared --with-client-ldflags=-non_shared
If you want to use egcs the following configure line worked for us:
CFLAGS="-O3 -fomit-frame-pointer" CXX=gcc \ CXXFLAGS="-O3 -fomit-frame-pointer -felide-constructors \ -fno-exceptions -fno-rtti" ./configure --prefix=/usr/local/mysql \ --disable-shared
Some known problems when running MySQL on Linux-Alpha:
gdb 4.18. You should download and use gdb 5.1 instead!
mysqld statically when using gcc, the
resulting image will core dump at start. In other words, don't
use --with-mysqld-ldflags=-all-static with gcc.
MySQL should work on MkLinux with the newest glibc package
(tested with glibc 2.0.7).
To get MySQL to work on Qube2, (Linux Mips), you need the
newest glibc libraries (glibc-2.0.7-29C2 is known to
work). You must also use the egcs C++ compiler
(egcs-1.0.2-9, gcc 2.95.2 or newer).
To get MySQL to compile on Linux IA64, we use the following compile line:
Using gcc-2.96:
CC=gcc CFLAGS="-O3 -fno-omit-frame-pointer" CXX=gcc \ CXXFLAGS="-O3 -fno-omit-frame-pointer -felide-constructors \ -fno-exceptions -fno-rtti" ./configure --prefix=/usr/local/mysql \ "--with-comment=Official MySQL binary" --with-extra-charsets=complex
On IA64 the MySQL client binaries are using shared libraries. This means
that if you install our binary distribution in some other place than
`/usr/local/mysql' you need to either modify `/etc/ld.so.conf'
or add the path to the directory where you have `libmysqlclient.so'
to the LD_LIBRARY_PATH environment variable.
See section A.3.1 Problems When Linking with the MySQL Client Library.
This section describes using MySQL on Windows. This information is also provided in the `README' file that comes with the MySQL Windows distribution. See section 2.1.2 Installing MySQL on Windows.
MySQL uses TCP/IP to connect a client to a server. (This will allow any machine on your network to connect to your MySQL server.) Because of this, you must install TCP/IP on your machine before starting MySQL. You can find TCP/IP on your Windows CD-ROM.
Note that if you are using an old Windows 95 release (for example OSR2), it's likely that you have an old Winsock package; MySQL requires Winsock 2! You can get the newest Winsock from http://www.microsoft.com/. Windows 98 has the new Winsock 2 library, so the above doesn't apply there.
To start the mysqld server, you should start an MS-DOS
window and type:
C:\> C:\mysql\bin\mysqld
This will start mysqld in the background without a window.
You can kill the MySQL server by executing:
C:\> C:\mysql\bin\mysqladmin -u root shutdown
This calls the MySQL administation utility as user `root', which is the default Administrator in the MySQL grant system. Please note that the MySQL grant system is wholly independent from any login users under Windows.
Note that Windows 95/98/Me don't support creation of named pipes.
So on those platforms, you can only use named pipes to connect to a
remote MySQL server running on a Windows NT/2000/XP server host.
(The MySQL server must also support named pipes, of course.
For example, using mysqld-opt under NT/2000/XP will not
allow named pipe connections. You should use either
mysqld-nt or mysqld-max-nt.)
If mysqld doesn't start, please check the
`\mysql\data\mysql.err' file to see if the server wrote any
message there to indicate the cause of the problem. You can also
try to start the server with mysqld --standalone; in this
case, you may get some useful information on the screen that may
help solve the problem.
The last option is to start mysqld with
--standalone --debug.
In this case mysqld will write a log file
`C:\mysqld.trace' that should contain the reason why
mysqld doesn't start. See section E.1.2 Creating Trace Files.
Use mysqld --help to display all the options that
mysqld understands!
To get MySQL to work with TCP/IP on Windows NT 4, you must install service pack 3 (or newer)!
Normally you should install MySQL as a service on Windows NT/2000/XP. In case the server was already running, first stop it using the following command:
C:\mysql\bin> mysqladmin -u root shutdown
This calls the MySQL administation utility as user `root',
which is the default Administrator in the MySQL grant system.
Please note that the MySQL grant system is wholly independent from
any login users under Windows.
Now install the server service:
C:\mysql\bin> mysqld-max-nt --install
If any options are required, they must be specified as
``Start parameters'' in the Windows Services
utility before you start the MySQL service.
The Services utility
(Windows Service Control Manager) can be found in the
Windows Control Panel (under Administrative Tools
on Windows 2000). It is advisable to close the Services utility
while performing the --install or --remove
operations, this prevents some odd errors.
For information about which server binary to run, see section 2.1.2.2 Preparing the Windows MySQL Environment.
Please note that from MySQL version 3.23.44, you have the choice
of set up the service as Manual instead (if you don't wish
the service to be started automatically during the boot process):
C:\mysql\bin> mysqld-max-nt --install-manual
The service is installed with the name MySQL. Once
installed, it can be immediately started from the Services
utility, or by using the command NET START MySQL.
Once running, mysqld-max-nt can be stopped using
mysqladmin, from the Services utility, or by using the
command NET STOP MySQL.
When running as a service, the operating system will automatically stop
the MySQL service on computer shutdown. In MySQL versions < 3.23.47,
Windows only waited for a few seconds for the shutdown to complete, and
killed the database server process if the time limit was exceeded
(potentially causing problems). For instance, at the next startup the
InnoDB storage engine had to do crash recovery. Starting from
MySQL version 3.23.48, the Windows will wait longer for the MySQL server
shutdown to complete. If you notice this is not enough for your
intallation, it is safest to run the MySQL server not as a service, but
from the Command prompt, and shut it down with mysqladmin shutdown.
There is a problem that Windows NT (but not Windows 2000/XP) by default only
waits 20 seconds for a service to shut down, and after that kills the
service process. You can increase this default by opening the Registry
Editor `\winnt\system32\regedt32.exe' and editing the value of
WaitToKillServiceTimeout at
`HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control'
in the Registry tree. Specify the new larger value in milliseconds,
for example 120000 to have Windows NT wait upto 120 seconds.
Please note that when run as a service, mysqld-max-nt
has no access to a console and so no messages can be seen.
Errors can be checked in `c:\mysql\data\mysql.err'.
If you have problems installing mysqld-max-nt as a
service, try starting it with the full path:
C:\> C:\mysql\bin\mysqld-max-nt --install
If this doesn't work, you can get mysqld-max-nt to
start properly by fixing the path in the registry!
If you don't want to start mysqld-max-nt as a service,
you can start it as follows:
C:\> C:\mysql\bin\mysqld-max-nt --standalone
or
C:\> C:\mysql\bin\mysqld --standalone --debug
The last method gives you a debug trace in `C:\mysqld.trace'. See section E.1.2 Creating Trace Files.
MySQL supports TCP/IP on all Windows platforms and named pipes on NT/2000/XP. The default is to use named pipes for local connections on NT/2000/XP and TCP/IP for all other cases if the client has TCP/IP installed. The host name specifies which protocol is used:
| Host name | Protocol |
| NULL (none) | On NT/2000/XP, try named pipes first; if that doesn't work, use TCP/IP. On 9x/Me, TCP/IP is used. |
| . | Named pipes |
| localhost | TCP/IP to current host |
| hostname | TCP/IP |
You can force a MySQL client to use named pipes by specifying the
--pipe option or by specifying . as the host name. Use the
--socket option to specify the name of the pipe.
In MySQL 4.1 you should use the --protocol=PIPE option.
Note that starting from 3.23.50, named pipes are only enabled if mysqld is
started with --enable-named-pipe. This is because some users
have experienced problems shutting down the MySQL server when one uses
named pipes.
You can test whether MySQL is working by executing the following commands:
C:\> C:\mysql\bin\mysqlshow C:\> C:\mysql\bin\mysqlshow -u root mysql C:\> C:\mysql\bin\mysqladmin version status proc C:\> C:\mysql\bin\mysql test
If mysqld is slow to answer to connections on Windows 9x/Me, there is
probably a problem with your DNS. In this case, start mysqld with
--skip-name-resolve and use only localhost and IP numbers in
the MySQL grant tables. You can also avoid DNS when connecting to a
mysqld-nt MySQL server running on NT/2000/XP by using the
--pipe argument to specify use of named pipes. This works for most
MySQL clients.
There are two versions of the MySQL command-line tool:
| Binary | Description |
mysql | Compiled on native Windows, which offers very limited text editing capabilities. |
mysqlc | Compiled with the Cygnus GNU compiler and libraries, which offers readline editing.
|
If you want to use mysqlc.exe, you must copy
`C:\mysql\lib\cygwinb19.dll' to your Windows system directory
(`\windows\system' or similar place).
The default privileges on Windows give all local users full privileges
to all databases without specifying a password. To make MySQL
more secure, you should set a password for all users and remove the row in
the mysql.user table that has Host='localhost' and
User=''.
You should also add a password for the root user. The following
example starts by removing the anonymous user that has all privileges,
then sets a root user password:
C:\> C:\mysql\bin\mysql mysql mysql> DELETE FROM user WHERE Host='localhost' AND User=''; mysql> QUIT C:\> C:\mysql\bin\mysqladmin reload C:\> C:\mysql\bin\mysqladmin -u root password your_password
After you've set the password, if you want to take down the mysqld
server, you can do so using this command:
C:\> mysqladmin --user=root --password=your_password shutdown
If you are using the old shareware version of MySQL Version
3.21 under Windows, the above command will fail with an error:
parse error near 'SET password'. The solution for
this is to download and upgrade to the latest MySQL version,
which is now freely available.
With the current MySQL versions you can easily add new users
and change privileges with GRANT and REVOKE commands.
See section 4.3.1 GRANT and REVOKE Syntax.
Here is a note about how to connect to get a secure connection to remote MySQL server with SSH (by David Carlson dcarlson@mplcomm.com):
SecureCRT from http://www.vandyke.com/.
Another option is f-secure from http://www.f-secure.com/. You
can also find some free ones on Google at
http://directory.google.com/Top/Computers/Security/Products_and_Tools/Cryptography/SSH/Clients/Windows/.
Host_Name = yourmysqlserver_URL_or_IP.
Set userid=your_userid to log in to your server (probably not the same
as your MySQL login/password.
local_port: 3306, remote_host: yourmysqlservername_or_ip, remote_port: 3306 )
or a local forward (Set port: 3306, host: localhost, remote port: 3306).
localhost
for the MySQL host server@-not yourmysqlservername.
You should now have an ODBC connection to MySQL, encrypted using SSH.
Beginning with MySQL Version 3.23.16, the mysqld-max
and mysql-max-nt servers in the MySQL distribution are
compiled with the -DUSE_SYMDIR option. This allows you to put a
database on different disk by adding a symbolic link to it
(in a manner similar to the way that symbolic links work on Unix).
On Windows, you make a symbolic link to a database by creating a file that contains the path to the destination directory and saving this in the `mysql_data' directory under the filename `database.sym'. Note that the symbolic link will be used only if the directory `mysql_data_dir\database' doesn't exist.
For example, if the MySQL data directory is `C:\mysql\data'
and you want to have database foo located at `D:\data\foo', you
should create the file `C:\mysql\data\foo.sym' that contains the
text D:\data\foo\. After that, all tables created in the database
foo will be created in `D:\data\foo'.
Note that because of the speed penalty you get when opening every table, we have not enabled this by default even if you have compiled MySQL with support for this. To enable symlinks you should put in your `my.cnf' or `my.ini' file the following entry:
[mysqld] use-symbolic-links
In MySQL 4.0 we will enable symlinks by default. Then you
should instead use the skip-symlink option if you want to
disable this.
In your source files, you should include `windows.h' before you include `mysql.h':
#if defined(_WIN32) || defined(_WIN64) #include <windows.h> #endif #include <mysql.h>
You can either link your code with the dynamic `libmysql.lib' library, which is just a wrapper to load in `libmysql.dll' on demand, or link with the static `mysqlclient.lib' library.
Note that as the mysqlclient libraries are compiled as threaded libraries, you should also compile your code to be multi-threaded!
MySQL-Windows has by now proven itself to be very stable. This version of MySQL has the same features as the corresponding Unix version with the following exceptions:
mysqld for an extended time on Windows 95 if your server handles
many connections! Other versions of Windows don't suffer from this bug.
pread() and pwrite() calls to be
able to mix INSERT and SELECT. Currently we use mutexes
to emulate pread()/pwrite(). We will, in the long run,
replace the file level interface with a virtual interface so that we can
use the readfile()/writefile() interface on NT/2000/XP to
get more speed.
The current implementation limits the number of open files MySQL
can use to 1024, which means that you will not be able to run as many
concurrent threads on NT/2000/XP as on Unix.
mysqladmin kill will not work on a sleeping connection.
mysqladmin shutdown can't abort as long as there are sleeping
connections.
DROP DATABASE
mysqladmin shutdown.
LOAD
DATA INFILE or SELECT ... INTO OUTFILE, you must double the `\'
character:
mysql> LOAD DATA INFILE "C:\\tmp\\skr.txt" INTO TABLE skr; mysql> SELECT * INTO OUTFILE 'C:\\tmp\\skr.txt' FROM skr;Alternatively, use Unix style filenames with `/' characters:
mysql> LOAD DATA INFILE "C:/tmp/skr.txt" INTO TABLE skr; mysql> SELECT * INTO OUTFILE 'C:/tmp/skr.txt' FROM skr;
Can't open named pipe error
error 2017: can't open named pipe to host: . pipe...This is because the release version of MySQL uses named pipes on NT by default. You can avoid this error by using the
--host=localhost
option to the new MySQL clients or create an option file
`C:\my.cnf' that contains the following information:
[client] host = localhostStarting from 3.23.50, named pipes are only enabled if
mysqld is started
with --enable-named-pipe.
Access denied for user error
Access denied for user: 'some-user@unknown'
to database 'mysql' when accessing a MySQL server on the same
machine, this means that MySQL can't resolve your host name
properly.
To fix this, you should create a file `\windows\hosts' with the
following information:
127.0.0.1 localhost
ALTER TABLE
ALTER TABLE statement, the table is locked
from usage by other threads. This has to do with the fact that on Windows,
you can't delete a file that is in use by another threads. (In the future,
we may find some way to work around this problem.)
DROP TABLE on a table that is in use by a MERGE table will
not work on Windows because the MERGE handler does the table mapping
hidden from the upper layer of MySQL. Because Windows doesn't allow you
to drop files that are open, you first must flush all MERGE
tables (with FLUSH TABLES) or drop the MERGE table before
dropping the table. We will fix this at the same time we introduce
VIEWs.
DATA DIRECTORY and INDEX DIRECTORY directives in
CREATE TABLE is ignored on Windows, because Windows doesn't support
symbolic links.
Here are some open issues for anyone who might want to help us with the Windows release:
MYSQL.DLL server. This should include everything in
a standard MySQL server, except thread creation. This will make
MySQL much easier to use in applications that don't need a true
client/server and don't need to access the server from other hosts.
mysqld as a service with --install (on NT)
it would be nice if you could also add default options on the command-line.
For the moment, the workaround is to list the parameters in the
`C:\my.cnf' file instead.
mysqld from the task manager.
For the moment, you must use mysqladmin shutdown.
readline to Windows for use in the mysql command-line tool.
mysql,
mysqlshow, mysqladmin, and mysqldump) would be nice.
mysqladmin kill on Windows.
mysqld always starts in the "C" locale and not in the default locale.
We would like to have mysqld use the current locale for the sort order.
Other Windows-specific issues are described in the `README' file that comes with the MySQL-Windows distribution.
On Solaris, you may run into trouble even before you get the MySQL
distribution unpacked! Solaris tar can't handle long file names, so
you may see an error like this when you unpack MySQL:
x mysql-3.22.12-beta/bench/Results/ATIS-mysql_odbc-NT_4.0-cmp-db2,\ informix,ms-sql,mysql,oracle,solid,sybase, 0 bytes, 0 tape blocks tar: directory checksum error
In this case, you must use GNU tar (gtar) to unpack the
distribution. You can find a precompiled copy for Solaris at
http://www.mysql.com/downloads/os-solaris.html.
Sun native threads work only on Solaris 2.5 and higher. For Version 2.4 and earlier, MySQL will automatically use MIT-pthreads. See section 2.3.6 MIT-pthreads Notes.
If you get the following error from configure:
checking for restartable system calls... configure: error can not run test programs while cross compiling
This means that you have something wrong with your compiler installation! In this case you should upgrade your compiler to a newer version. You may also be able to solve this problem by inserting the following row into the `config.cache' file:
ac_cv_sys_restartable_syscalls=${ac_cv_sys_restartable_syscalls='no'}
If you are using Solaris on a SPARC, the recommended compiler is
gcc 2.95.2. You can find this at http://gcc.gnu.org/.
Note that egcs 1.1.1 and gcc 2.8.1 don't work reliably on
SPARC!
The recommended configure line when using gcc 2.95.2 is:
CC=gcc CFLAGS="-O3" \ CXX=gcc CXXFLAGS="-O3 -felide-constructors -fno-exceptions -fno-rtti" \ ./configure --prefix=/usr/local/mysql --with-low-memory --enable-assembler
If you have an UltraSPARC, you can get 4% more performance by adding "-mcpu=v8 -Wa,-xarch=v8plusa" to CFLAGS and CXXFLAGS.
If you have Sun's Forte 5.0 (or newer) compiler, you can
run configure like this:
CC=cc CFLAGS="-Xa -fast -native -xstrconst -mt" \ CXX=CC CXXFLAGS="-noex -mt" \ ./configure --prefix=/usr/local/mysql --enable-assembler
You can create a 64 bit binary with:
CC=cc CFLAGS="-Xa -fast -native -xstrconst -mt -xarch=v9" \ CXX=CC CXXFLAGS="-noex -mt -xarch=v9" ASFLAGS="-xarch=v9" \ ./configure --prefix=/usr/local/mysql --enable-assembler
In the MySQL benchmarks, we got a 4% speedup on an UltraSPARC when using Forte 5.0 in 32 bit mode compared to using gcc 3.2 with -mcpu flags.
If you create a 64 bit binary, it's 4 % slower than the 32 bit binary, but mysqld can instead handle more treads and memory.
If you get a problem with fdatasync or sched_yield,
you can fix this by adding LIBS=-lrt to the configure line
The following paragraph is only relevant for older compilers than WorkShop 5.3:
You may also have to edit the configure script to change this line:
#if !defined(__STDC__) || __STDC__ != 1
to this:
#if !defined(__STDC__)
If you turn on __STDC__ with the -Xc option, the Sun compiler
can't compile with the Solaris `pthread.h' header file. This is a Sun
bug (broken compiler or broken include file).
If mysqld issues the error message shown here when you run it, you have
tried to compile MySQL with the Sun compiler without enabling the
multi-thread option (-mt):
libc internal error: _rmutex_unlock: rmutex not held
Add -mt to CFLAGS and CXXFLAGS and try again.
If you are using the SFW version of gcc (which comes with Solaris 8),
you must add `/opt/sfw/lib' to the environment variable
LD_LIBRARY_PATH before running configure.
If you are using the gcc available from sunfreeware.com, you may
have many problems. You should recompile gcc and GNU binutils on the
machine you will be running them from to avoid any problems.
If you get the following error when compiling MySQL with gcc,
it means that your gcc is not configured for your version of Solaris:
shell> gcc -O3 -g -O2 -DDBUG_OFF -o thr_alarm ... ./thr_alarm.c: In function `signal_hand': ./thr_alarm.c:556: too many arguments to function `sigwait'
The proper thing to do in this case is to get the newest version of
gcc and compile it with your current gcc compiler! At
least for Solaris 2.5, almost all binary versions of gcc have
old, unusable include files that will break all programs that use
threads (and possibly other programs)!
Solaris doesn't provide static versions of all system libraries
(libpthreads and libdl), so you can't compile MySQL
with --static. If you try to do so, you will get the error:
ld: fatal: library -ldl: not found or undefined reference to `dlopen' or cannot find -lrt
If too many processes try to connect very rapidly to mysqld, you will
see this error in the MySQL log:
Error in accept: Protocol error
You might try starting the server with the --set-variable back_log=50
option as a workaround for this. Please note that --set-variable is
deprecated since MySQL 4.0, just use --back_log=50 on its own.
See section 4.1.1 mysqld Command-line Options.
If you are linking your own MySQL client, you might get the following error when you try to execute it:
ld.so.1: ./my: fatal: libmysqlclient.so.#: open failed: No such file or directory
The problem can be avoided by one of the following methods:
-Lpath):
-Wl,r/full-path-to-libmysqlclient.so.
LD_RUN_PATH environment variable before running your client.
If you have problems with configure trying to link with -lz and
you don't have zlib installed, you have two options:
--with-named-z-libs=no.
If you are using gcc and have problems with loading UDF functions
into MySQL, try adding -lgcc to the link line for the
UDF function.
If you would like MySQL to start automatically, you can copy `support-files/mysql.server' to `/etc/init.d' and create a symbolic link to it named `/etc/rc3.d/S99mysql.server'.
As Solaris doesn't support core files for setuid() applications,
you can't get a core file from mysqld if you are using the
--user option.
You can normally use a Solaris 2.6 binary on Solaris 2.7 and 2.8. Most of the Solaris 2.6 issues also apply for Solaris 2.7 and 2.8.
Note that MySQL Version 3.23.4 and above should be able to autodetect new versions of Solaris and enable workarounds for the following problems!
Solaris 2.7 / 2.8 has some bugs in the include files. You may see the
following error when you use gcc:
/usr/include/widec.h:42: warning: `getwc' redefined /usr/include/wchar.h:326: warning: this is the location of the previous definition
If this occurs, you can do the following to fix the problem:
Copy /usr/include/widec.h to
.../lib/gcc-lib/os/gcc-version/include and change line 41 from:
#if !defined(lint) && !defined(__lint) to #if !defined(lint) && !defined(__lint) && !defined(getwc)
Alternatively, you can edit `/usr/include/widec.h' directly. Either
way, after you make the fix, you should remove `config.cache' and run
configure again!
If you get errors like this when you run make, it's because
configure didn't detect the `curses.h' file (probably
because of the error in `/usr/include/widec.h'):
In file included from mysql.cc:50: /usr/include/term.h:1060: syntax error before `,' /usr/include/term.h:1081: syntax error before `;'
The solution to this is to do one of the following:
CFLAGS=-DHAVE_CURSES_H CXXFLAGS=-DHAVE_CURSES_H ./configure.
#define HAVE_TERM line from `config.h' file and
run make again.
If you get a problem that your linker can't find -lz when linking
your client program, the problem is probably that your `libz.so' file is
installed in `/usr/local/lib'. You can fix this by one of the
following methods:
LD_LIBRARY_PATH.
--with-named-z-libs=no option.
On Solaris 2.8 on x86, mysqld will core dump if you run
'strip' in.
If you are using gcc or egcs on Solaris x86 and you
experience problems with core dumps under load, you should use the
following configure command:
CC=gcc CFLAGS="-O3 -fomit-frame-pointer -DHAVE_CURSES_H" \ CXX=gcc \ CXXFLAGS="-O3 -fomit-frame-pointer -felide-constructors -fno-exceptions \ -fno-rtti -DHAVE_CURSES_H" \ ./configure --prefix=/usr/local/mysql
This will avoid problems with the libstdc++ library and with C++
exceptions.
If this doesn't help, you should compile a debug version and run
it with a trace file or under gdb. See section E.1.3 Debugging mysqld under gdb.
This section provides information for the various BSD flavours, as well as specific versions within those.
FreeBSD 3.x is recommended for running MySQL since the thread package is much more integrated.
The easiest and therefore the preferred way to install is to use the mysql-server and mysql-client ports available on http://www.freebsd.org/.
Using these gives you:
It is recommended you use MIT-pthreads on FreeBSD 2.x and native threads on
Versions 3 and up. It is possible to run with native threads on some late
2.2.x versions but you may encounter problems shutting down mysqld.
The MySQL `Makefile's require GNU make (gmake) to work. If
you want to compile MySQL you need to install GNU make first.
Be sure to have your name resolver setup correct. Otherwise, you may
experience resolver delays or failures when connecting to mysqld.
Make sure that the localhost entry in the `/etc/hosts' file is
correct (otherwise, you will have problems connecting to the database). The
`/etc/hosts' file should start with a line:
127.0.0.1 localhost localhost.your.domain
The recommended way to compile and install MySQL on FreeBSD with gcc (2.95.2 and up) is:
CC=gcc CFLAGS="-O2 -fno-strength-reduce" \ CXX=gcc CXXFLAGS="-O2 -fno-rtti -fno-exceptions -felide-constructors \ -fno-strength-reduce" \ ./configure --prefix=/usr/local/mysql --enable-assembler gmake gmake install ./scripts/mysql_install_db cd /usr/local/mysql ./bin/mysqld_safe &
If you notice that configure will use MIT-pthreads, you should read
the MIT-pthreads notes. See section 2.3.6 MIT-pthreads Notes.
If you get an error from make install that it can't find
`/usr/include/pthreads', configure didn't detect that you need
MIT-pthreads. This is fixed by executing these commands:
shell> rm config.cache shell> ./configure --with-mit-threads
FreeBSD is also known to have a very low default file handle limit.
See section A.2.16 File Not Found. Uncomment the ulimit -n section in
safe_mysqld or raise the limits for the mysqld user in /etc/login.conf
(and rebuild it with cap_mkdb /etc/login.conf). Also be sure you set the
appropriate class for this user in the password file if you are not
using the default (use: chpass mysqld-user-name). See section 4.7.2 safe_mysqld, The Wrapper Around mysqld.
If you have a lot of memory you should consider rebuilding
the kernel to allow MySQL to take more than 512M of RAM.
Take a look at option MAXDSIZ in the LINT config
file for more info.
If you get problems with the current date in MySQL, setting the
TZ variable will probably help. See section F Environment Variables.
To get a secure and stable system you should only use FreeBSD kernels
that are marked -RELEASE.
To compile on NetBSD you need GNU make. Otherwise, the compile will
crash when make tries to run lint on C++ files.
On OpenBSD Version 2.5, you can compile MySQL with native threads with the following options:
CFLAGS=-pthread CXXFLAGS=-pthread ./configure --with-mit-threads=no
Our users have reported that OpenBSD 2.8 has a threading bug which causes problems with MySQL. The OpenBSD Developers have fixed the problem, but as of January 25th, 2001, it's only available in the ``-current'' branch. The symptoms of this threading bug are: slow response, high load, high CPU usage, and crashes.
If you get an error like Error in accept:: Bad file descriptor or
error 9 when trying to open tables or directories, the problem is probably
that you haven't allocated enough file descriptors for MySQL.
In this case try starting safe_mysqld as root with the following
options:
--user=mysql --open-files-limit=2048
If you get the following error when compiling MySQL, your
ulimit value for virtual memory is too low:
item_func.h: In method `Item_func_ge::Item_func_ge(const Item_func_ge &)': item_func.h:28: virtual memory exhausted make[2]: *** [item_func.o] Error 1
Try using ulimit -v 80000 and run make again. If this
doesn't work and you are using bash, try switching to csh
or sh; some BSDI users have reported problems with bash
and ulimit.
If you are using gcc, you may also use have to use the
--with-low-memory flag for configure to be able to compile
`sql_yacc.cc'.
If you get problems with the current date in MySQL, setting the
TZ variable will probably help. See section F Environment Variables.
Upgrade to BSD/OS Version 3.1. If that is not possible, install BSDIpatch M300-038.
Use the following command when configuring MySQL:
shell> env CXX=shlicc++ CC=shlicc2 \
./configure \
--prefix=/usr/local/mysql \
--localstatedir=/var/mysql \
--without-perl \
--with-unix-socket-path=/var/mysql/mysql.sock
The following is also known to work:
shell> env CC=gcc CXX=gcc CXXFLAGS=-O3 \
./configure \
--prefix=/usr/local/mysql \
--with-unix-socket-path=/var/mysql/mysql.sock
You can change the directory locations if you wish, or just use the defaults by not specifying any locations.
If you have problems with performance under heavy load, try using the
--skip-thread-priority option to mysqld! This will run
all threads with the same priority; on BSDI Version 3.1, this gives better
performance (at least until BSDI fixes their thread scheduler).
If you get the error virtual memory exhausted while compiling,
you should try using ulimit -v 80000 and run make again.
If this doesn't work and you are using bash, try switching to
csh or sh; some BSDI users have reported problems with
bash and ulimit.
BSDI Version 4.x has some thread-related bugs. If you want to use MySQL on this, you should install all thread-related patches. At least M400-023 should be installed.
On some BSDI Version 4.x systems, you may get problems with shared libraries.
The symptom is that you can't execute any client programs, for example,
mysqladmin. In this case you need to reconfigure not to use
shared libraries with the --disable-shared option to configure.
Some customers have had problems on BSDI 4.0.1 that the mysqld
binary after a while can't open tables. This is because some
library/system related bug causes mysqld to change current
directory without asking for this!
The fix is to either upgrade to 3.23.34 or after running configure
remove the line #define HAVE_REALPATH from config.h
before running make.
Note that the above means that you can't symbolic link a database directories to another database directory or symbolic link a table to another database on BSDI! (Making a symbolic link to another disk is okay).
MySQL should work without any problems on Mac OS X 10.x (Darwin). You don't need the pthread patches for this OS!
This also applies to Mac OS X 10.x Server. Compiling for the Server platform is the same as for the client version of Mac OS X. However please note that MySQL comes preinstalled on the Server!
See section 2.1.3 Installing MySQL on Mac OS X.
Before trying to configure MySQL on Mac OS X server you must first install the pthread package from http://www.prnet.de/RegEx/mysql.html.
Our binary for Mac OS X is compiled on Darwin 6.3 with the following configure line:
CC=gcc CFLAGS="-O3 -fno-omit-frame-pointer" CXX=gcc \ CXXFLAGS="-O3 -fno-omit-frame-pointer -felide-constructors \ -fno-exceptions -fno-rtti" ./configure --prefix=/usr/local/mysql \ --with-extra-charsets=complex --enable-thread-safe-client \ --enable-local-infile --disable-shared
You might want to also add aliases to your shell's resource file to
access mysql and mysqladmin from the command-line:
alias mysql '/usr/local/mysql/bin/mysql' alias mysqladmin '/usr/local/mysql/bin/mysqladmin'
Alternatively, you could simply add /usr/local/mysql/bin to
your PATH environment variable, e.g. by adding the following
to `$HOME/.tcshrc':
setenv PATH $PATH:/usr/local/bin
Some of the binary distributions of MySQL for HP-UX are distributed as an HP depot file and as a tar file. To use the depot file you must be running at least HP-UX 10.x to have access to HP's software depot tools.
The HP version of MySQL was compiled on an HP 9000/8xx server under HP-UX 10.20, and uses MIT-pthreads. It is known to work well under this configuration. MySQL Version 3.22.26 and newer can also be built with HP's native thread package.
Other configurations that may work:
The following configurations almost definitely won't work:
To install the distribution, use one of the commands here, where
/path/to/depot is the full pathname of the depot file:
shell> /usr/sbin/swinstall -s /path/to/depot mysql.full
shell> /usr/sbin/swinstall -s /path/to/depot mysql.server
shell> /usr/sbin/swinstall -s /path/to/depot mysql.client
shell> /usr/sbin/swinstall -s /path/to/depot mysql.developer
The depot places binaries and libraries in `/opt/mysql' and data in
`/var/opt/mysql'. The depot also creates the appropriate entries in
`/etc/init.d' and `/etc/rc2.d' to start the server automatically
at boot time. Obviously, this entails being root to install.
To install the HP-UX tar.gz distribution, you must have a copy of GNU
tar.
There are a couple of small problems when compiling MySQL on
HP-UX. We recommend that you use gcc instead of the HP-UX native
compiler, because gcc produces better code!
We recommend using gcc 2.95 on HP-UX. Don't use high optimisation flags (like -O6) as this may not be safe on HP-UX.
The following configure line should work with gcc 2.95:
CFLAGS="-I/opt/dce/include -fpic" \ CXXFLAGS="-I/opt/dce/include -felide-constructors -fno-exceptions \ -fno-rtti" CXX=gcc ./configure --with-pthread \ --with-named-thread-libs='-ldce' --prefix=/usr/local/mysql --disable-shared
The following configure line should work with gcc 3.1:
CFLAGS="-DHPUX -I/opt/dce/include -O3 -fPIC" CXX=gcc \ CXXFLAGS="-DHPUX -I/opt/dce/include -felide-constructors -fno-exceptions \ -fno-rtti -O3 -fPIC" ./configure --prefix=/usr/local/mysql \ --with-extra-charsets=complex --enable-thread-safe-client \ --enable-local-infile --with-pthread \ --with-named-thread-libs=-ldce --with-lib-ccflags=-fPIC --disable-shared
For HP-UX Version 11.x we recommend MySQL Version 3.23.15 or later.
Because of some critical bugs in the standard HP-UX libraries, you should install the following patches before trying to run MySQL on HP-UX 11.0:
PHKL_22840 Streams cumulative PHNE_22397 ARPA cumulative
This will solve the problem of getting EWOULDBLOCK from recv()
and EBADF from accept() in threaded applications.
If you are using gcc 2.95.1 on an unpatched HP-UX 11.x system,
you will get the error:
In file included from /usr/include/unistd.h:11,
from ../include/global.h:125,
from mysql_priv.h:15,
from item.cc:19:
/usr/include/sys/unistd.h:184: declaration of C function ...
/usr/include/sys/pthread.h:440: previous declaration ...
In file included from item.h:306,
from mysql_priv.h:158,
from item.cc:19:
The problem is that HP-UX doesn't define pthreads_atfork() consistently.
It has conflicting prototypes in
`/usr/include/sys/unistd.h':184 and
`/usr/include/sys/pthread.h':440 (details below).
One solution is to copy `/usr/include/sys/unistd.h' into `mysql/include' and edit `unistd.h' and change it to match the definition in `pthread.h'. Here's the diff:
183,184c183,184 < extern int pthread_atfork(void (*prepare)(), void (*parent)(), < void (*child)()); --- > extern int pthread_atfork(void (*prepare)(void), void (*parent)(void), > void (*child)(void));
After this, the following configure line should work:
CFLAGS="-fomit-frame-pointer -O3 -fpic" CXX=gcc \ CXXFLAGS="-felide-constructors -fno-exceptions -fno-rtti -O3" \ ./configure --prefix=/usr/local/mysql --disable-shared
If you are using MySQL 4.0.5 with the HP-UX compiler you can use: (tested with cc B.11.11.04):
CC=cc CXX=aCC CFLAGS=+DD64 CXXFLAGS=+DD64 ./configure --with-extra-character-set=complex
You can ignore any errors of the following type:
aCC: warning 901: unknown option: `-3': use +help for online documentation
If you get the following error from configure
checking for cc option to accept ANSI C... no configure: error: MySQL requires a ANSI C compiler (and a C++ compiler). Try gcc. See the Installation chapter in the Reference Manual.
Check that you don't have the path to the K&R compiler before the path to the HP-UX C and C++ compiler.
Another reason for not beeing able to compile is that you didn't define
the +DD64 flags above.
Automatic detection of xlC is missing from Autoconf, so a
configure command something like this is needed when compiling
MySQL (This example uses the IBM compiler):
export CC="xlc_r -ma -O3 -qstrict -qoptimize=3 -qmaxmem=8192 " export CXX="xlC_r -ma -O3 -qstrict -qoptimize=3 -qmaxmem=8192" export CFLAGS="-I /usr/local/include" export LDFLAGS="-L /usr/local/lib" export CPPFLAGS=$CFLAGS export CXXFLAGS=$CFLAGS ./configure --prefix=/usr/local \ --localstatedir=/var/mysql \ --sysconfdir=/etc/mysql \ --sbindir='/usr/local/bin' \ --libexecdir='/usr/local/bin' \ --enable-thread-safe-client \ --enable-large-files
Above are the options used to compile the MySQL distribution that can be found at http://www-frec.bull.com/.
If you change the -O3 to -O2 in the above configure line,
you must also remove the -qstrict option (this is a limitation in
the IBM C compiler).
If you are using gcc or egcs to compile MySQL, you
must use the -fno-exceptions flag, as the exception
handling in gcc/egcs is not thread-safe! (This is tested with
egcs 1.1.) There are also some known problems with IBM's assembler,
which may cause it to generate bad code when used with gcc.
We recommend the following configure line with egcs and
gcc 2.95 on AIX:
CC="gcc -pipe -mcpu=power -Wa,-many" \ CXX="gcc -pipe -mcpu=power -Wa,-many" \ CXXFLAGS="-felide-constructors -fno-exceptions -fno-rtti" \ ./configure --prefix=/usr/local/mysql --with-low-memory
The -Wa,-many is necessary for the compile to be successful. IBM is
aware of this problem but is in to hurry to fix it because of the workaround
available. We don't know if the -fno-exceptions is required with
gcc 2.95, but as MySQL doesn't use exceptions and the above
option generates faster code, we recommend that you should always use this
option with egcs / gcc.
If you get a problem with assembler code try changing the -mcpu=xxx to match your CPU. Typically power2, power, or powerpc may need to be used, alternatively you might need to use 604 or 604e. I'm not positive but I would think using "power" would likely be safe most of the time, even on a power2 machine.
If you don't know what your CPU is then do a "uname -m", this will give you back a string that looks like "000514676700", with a format of xxyyyyyymmss where xx and ss are always 0's, yyyyyy is a unique system id and mm is the id of the CPU Planar. A chart of these values can be found at http://publib.boulder.ibm.com/doc_link/en_US/a_doc_lib/cmds/aixcmds5/uname.htm. This will give you a machine type and a machine model you can use to determine what type of CPU you have.
If you have problems with signals (MySQL dies unexpectedly under high load) you may have found an OS bug with threads and signals. In this case you can tell MySQL not to use signals by configuring with:
shell> CFLAGS=-DDONT_USE_THR_ALARM CXX=gcc \
CXXFLAGS="-felide-constructors -fno-exceptions -fno-rtti \
-DDONT_USE_THR_ALARM" \
./configure --prefix=/usr/local/mysql --with-debug --with-low-memory
This doesn't affect the performance of MySQL, but has the side
effect that you can't kill clients that are ``sleeping'' on a connection with
mysqladmin kill or mysqladmin shutdown. Instead, the client
will die when it issues its next command.
On some versions of AIX, linking with libbind.a makes
getservbyname core dump. This is an AIX bug and should be reported
to IBM.
For AIX 4.2.1 and gcc you have to do the following changes.
After configuring, edit `config.h' and `include/my_config.h' and change the line that says
#define HAVE_SNPRINTF 1
to
#undef HAVE_SNPRINTF
And finally, in `mysqld.cc' you need to add a prototype for initgoups.
#ifdef _AIX41 extern "C" int initgroups(const char *,int); #endif
If you need to allocate a lot of memory to the mysqld process, it's not
enough to just set 'ulimit -d unlimited'. You may also have to set
in mysqld_safe something like:
export LDR_CNTRL='MAXDATA=0x80000000'
You can find more about using a lot of memory at: http://publib16.boulder.ibm.com/pseries/en_US/aixprggd/genprogc/lrg_prg_support.htm.
On SunOS 4, MIT-pthreads is needed to compile MySQL, which in turn
means you will need GNU make.
Some SunOS 4 systems have problems with dynamic libraries and libtool.
You can use the following configure line to avoid this problem:
shell> ./configure --disable-shared --with-mysqld-ldflags=-all-static
When compiling readline, you may get warnings about duplicate defines.
These may be ignored.
When compiling mysqld, there will be some implicit declaration
of function warnings. These may be ignored.
If you are using egcs 1.1.2 on Digital Unix, you should upgrade to gcc 2.95.2, as egcs on DEC has some serious bugs!
When compiling threaded programs under Digital Unix, the documentation
recommends using the -pthread option for cc and cxx and
the libraries -lmach -lexc (in addition to -lpthread). You
should run configure something like this:
CC="cc -pthread" CXX="cxx -pthread -O" \ ./configure --with-named-thread-libs="-lpthread -lmach -lexc -lc"
When compiling mysqld, you may see a couple of warnings like this:
mysqld.cc: In function void handle_connections()': mysqld.cc:626: passing long unsigned int *' as argument 3 of accept(int,sockadddr *, int *)'
You can safely ignore these warnings. They occur because configure
can detect only errors, not warnings.
If you start the server directly from the command-line, you may have problems
with it dying when you log out. (When you log out, your outstanding processes
receive a SIGHUP signal.) If so, try starting the server like this:
shell> nohup mysqld [options] &
nohup causes the command following it to ignore any SIGHUP
signal sent from the terminal. Alternatively, start the server by running
safe_mysqld, which invokes mysqld using nohup for you.
See section 4.7.2 safe_mysqld, The Wrapper Around mysqld.
If you get a problem when compiling mysys/get_opt.c, just remove the line #define _NO_PROTO from the start of that file!
If you are using Compac's CC compiler, the following configure line should work:
CC="cc -pthread" CFLAGS="-O4 -ansi_alias -ansi_args -fast -inline speed all -arch host" CXX="cxx -pthread" CXXFLAGS="-O4 -ansi_alias -ansi_args -fast -inline speed all -arch host \ -noexceptions -nortti" export CC CFLAGS CXX CXXFLAGS ./configure \ --prefix=/usr/local/mysql \ --with-low-memory \ --enable-large-files \ --enable-shared=yes \ --with-named-thread-libs="-lpthread -lmach -lexc -lc" gnumake
If you get a problem with libtool, when compiling with shared libraries
as above, when linking mysql, you should be able to get around
this by issuing:
cd mysql /bin/sh ../libtool --mode=link cxx -pthread -O3 -DDBUG_OFF \ -O4 -ansi_alias -ansi_args -fast -inline speed \ -speculate all \ -arch host -DUNDEF_HAVE_GETHOSTBYNAME_R \ -o mysql mysql.o readline.o sql_string.o completion_hash.o \ ../readline/libreadline.a -lcurses \ ../libmysql/.libs/libmysqlclient.so -lm cd .. gnumake gnumake install scripts/mysql_install_db
If you have problems compiling and have DEC CC and gcc
installed, try running configure like this:
CC=cc CFLAGS=-O CXX=gcc CXXFLAGS=-O3 \ ./configure --prefix=/usr/local/mysql
If you get problems with the `c_asm.h' file, you can create and use a 'dummy' `c_asm.h' file with:
touch include/c_asm.h CC=gcc CFLAGS=-I./include \ CXX=gcc CXXFLAGS=-O3 \ ./configure --prefix=/usr/local/mysql
Note that the following problems with the ld program can be fixed
by downloading the latest DEC (Compaq) patch kit from:
http://ftp.support.compaq.com/public/unix/.
On OSF/1 V4.0D and compiler "DEC C V5.6-071 on Digital Unix V4.0 (Rev. 878)"
the compiler had some strange behaviour (undefined asm symbols).
/bin/ld also appears to be broken (problems with _exit
undefined errors occuring while linking mysqld). On this system, we
have managed to compile MySQL with the following configure
line, after replacing /bin/ld with the version from OSF 4.0C:
CC=gcc CXX=gcc CXXFLAGS=-O3 ./configure --prefix=/usr/local/mysql
With the Digital compiler "C++ V6.1-029", the following should work:
CC=cc -pthread
CFLAGS=-O4 -ansi_alias -ansi_args -fast -inline speed -speculate all \
-arch host
CXX=cxx -pthread
CXXFLAGS=-O4 -ansi_alias -ansi_args -fast -inline speed -speculate all \
-arch host -noexceptions -nortti
export CC CFLAGS CXX CXXFLAGS
./configure --prefix=/usr/mysql/mysql --with-mysqld-ldflags=-all-static \
--disable-shared --with-named-thread-libs="-lmach -lexc -lc"
In some versions of OSF/1, the alloca() function is broken. Fix
this by removing the line in `config.h' that defines 'HAVE_ALLOCA'.
The alloca() function also may have an incorrect prototype in
/usr/include/alloca.h. This warning resulting from this can be ignored.
configure will use the following thread libraries automatically:
--with-named-thread-libs="-lpthread -lmach -lexc -lc".
When using gcc, you can also try running configure like this:
shell> CFLAGS=-D_PTHREAD_USE_D4 CXX=gcc CXXFLAGS=-O3 ./configure ...
If you have problems with signals (MySQL dies unexpectedly under high load), you may have found an OS bug with threads and signals. In this case you can tell MySQL not to use signals by configuring with:
shell> CFLAGS=-DDONT_USE_THR_ALARM \
CXXFLAGS=-DDONT_USE_THR_ALARM \
./configure ...
This doesn't affect the performance of MySQL, but has the side
effect that you can't kill clients that are ``sleeping'' on a connection with
mysqladmin kill or mysqladmin shutdown. Instead, the client
will die when it issues its next command.
With gcc 2.95.2, you will probably run into the following compile error:
sql_acl.cc:1456: Internal compiler error in `scan_region', at except.c:2566 Please submit a full bug report.
To fix this you should change to the sql directory and do a ``cut
and paste'' of the last gcc line, but change -O3 to
-O0 (or add -O0 immediately after gcc if you don't
have any -O option on your compile line). After this is done you
can just change back to the top-level directly and run make
again.
If you are using Irix Version 6.5.3 or newer mysqld will only be able to
create threads if you run it as a user with CAP_SCHED_MGT
privileges (like root) or give the mysqld server this privilege
with the following shell command:
shell> chcap "CAP_SCHED_MGT+epi" /opt/mysql/libexec/mysqld
You may have to undefine some things in `config.h' after running
configure and before compiling.
In some Irix implementations, the alloca() function is broken. If the
mysqld server dies on some SELECT statements, remove the lines
from `config.h' that define HAVE_ALLOC and HAVE_ALLOCA_H.
If mysqladmin create doesn't work, remove the line from `config.h'
that defines HAVE_READDIR_R. You may have to remove the
HAVE_TERM_H line as well.
SGI recommends that you install all of the patches on this page as a set: http://support.sgi.com/surfzone/patches/patchset/6.2_indigo.rps.html
At the very minimum, you should install the latest kernel rollup, the
latest rld rollup, and the latest libc rollup.
You definitely need all the POSIX patches on this page, for pthreads support:
http://support.sgi.com/surfzone/patches/patchset/6.2_posix.rps.html
If you get the something like the following error when compiling `mysql.cc':
"/usr/include/curses.h", line 82: error(1084): invalid combination of type
Type the following in the top-level directory of your MySQL source tree:
shell> extra/replace bool curses_bool < /usr/include/curses.h \ > include/curses.h shell> make
There have also been reports of scheduling problems. If only one thread is running, things go slow. Avoid this by starting another client. This may lead to a 2-to-10-fold increase in execution speed thereafter for the other thread. This is a poorly understood problem with Irix threads; you may have to improvise to find solutions until this can be fixed.
If you are compiling with gcc, you can use the following
configure command:
CC=gcc CXX=gcc CXXFLAGS=-O3 \ ./configure --prefix=/usr/local/mysql --enable-thread-safe-client \ --with-named-thread-libs=-lpthread
On Irix 6.5.11 with native Irix C and C++ compilers ver. 7.3.1.2, the following is reported to work
CC=cc CXX=CC CFLAGS='-O3 -n32 -TARG:platform=IP22 -I/usr/local/include \ -L/usr/local/lib' CXXFLAGS='-O3 -n32 -TARG:platform=IP22 \ -I/usr/local/include -L/usr/local/lib' ./configure \ --prefix=/usr/local/mysql --with-innodb --with-berkeley-db \ --with-libwrap=/usr/local \ --with-named-curses-libs=/usr/local/lib/libncurses.a
The current port is tested only on a ``sco3.2v5.0.4'' and ``sco3.2v5.0.5'' system. There has also been a lot of progress on a port to ``sco 3.2v4.2''.
For the moment the recommended compiler on OpenServer is gcc 2.95.2. With this you should be able to compile MySQL with just:
CC=gcc CXX=gcc ./configure ... (options)
./configure in the `threads/src' directory and select
the SCO OpenServer option. This command copies `Makefile.SCO5' to
`Makefile'.
make.
cd to the `thread/src' directory, and run make
install.
make when making MySQL.
safe_mysqld as root, you probably will get only the
default 110 open files per process. mysqld will write a note about this
in the log file.
configure command should work:
shell> ./configure --prefix=/usr/local/mysql --disable-shared
configure command should work:
shell> CFLAGS="-D_XOPEN_XPG4" CXX=gcc CXXFLAGS="-D_XOPEN_XPG4" \
./configure \
--prefix=/usr/local/mysql \
--with-named-thread-libs="-lgthreads -lsocket -lgen -lgthreads" \
--with-named-curses-libs="-lcurses"
You may get some problems with some include files. In this case, you can
find new SCO-specific include files at
http://www.mysql.com/Downloads/SCO/SCO-3.2v4.2-includes.tar.gz.
You should unpack this file in the `include' directory of your
MySQL source tree.
Caldera (SCO) development notes:
mysqld
with -lgthreads -lsocket -lgthreads.
malloc. If you encounter problems with memory usage,
make sure that `gmalloc.o' is included in `libgthreads.a' and
`libgthreads.so'.
read(),
write(), getmsg(), connect(), accept(),
select(), and wait().
If you want to install DBI on Caldera (SCO), you have to edit the `Makefile' in DBI-xxx and each subdirectory.
Note that the following assumes gcc 2.95.2 or newer:
OLD: NEW: CC = cc CC = gcc CCCDLFLAGS = -KPIC -W1,-Bexport CCCDLFLAGS = -fpic CCDLFLAGS = -wl,-Bexport CCDLFLAGS = LD = ld LD = gcc -G -fpic LDDLFLAGS = -G -L/usr/local/lib LDDLFLAGS = -L/usr/local/lib LDFLAGS = -belf -L/usr/local/lib LDFLAGS = -L/usr/local/lib LD = ld LD = gcc -G -fpic OPTIMISE = -Od OPTIMISE = -O1 OLD: CCCFLAGS = -belf -dy -w0 -U M_XENIX -DPERL_SCO5 -I/usr/local/include NEW: CCFLAGS = -U M_XENIX -DPERL_SCO5 -I/usr/local/include
This is because the Perl dynaloader will not load the DBI modules
if they were compiled with icc or cc.
Perl works best when compiled with cc.
You must use a version of MySQL at least as recent as Version 3.22.13 because that version fixes some portability problems under Unixware.
We have been able to compile MySQL with the following configure
command on Unixware Version 7.0.1:
CC=cc CXX=CC ./configure --prefix=/usr/local/mysql
If you want to use gcc, you must use gcc 2.95.2 or newer.
Caldera provides libsocket.so.2 at ftp://stage.caldera.com/pub/security/tools for pre-OSR506 security fixes. Also, the telnetd fix at ftp://stage.caldera.com/pub/security/openserver/CSSA-2001-SCO.10/ as both libsocket.so.2 and libresolv.so.1 with instructions for installing on pre-OSR506 systems.
It's probably a good idea to install the above patches before trying to compile/use MySQL.
MySQL uses quite a few open files. Because of this, you should add something like the following to your `CONFIG.SYS' file:
SET EMXOPT=-c -n -h1024
If you don't do this, you will probably run into the following error:
File 'xxxx' not found (Errcode: 24)
When using MySQL with OS/2 Warp 3, FixPack 29 or above is required. With OS/2 Warp 4, FixPack 4 or above is required. This is a requirement of the Pthreads library. MySQL must be installed in a partition that supports long filenames such as HPFS, FAT32, etc.
The `INSTALL.CMD' script must be run from OS/2's own `CMD.EXE' and may not work with replacement shells such as `4OS2.EXE'.
The `scripts/mysql-install-db' script has been renamed. It is now called `install.cmd' and is a REXX script, which will set up the default MySQL security settings and create the WorkPlace Shell icons for MySQL.
Dynamic module support is compiled in but not fully tested. Dynamic modules should be compiled using the Pthreads run-time library.
gcc -Zdll -Zmt -Zcrtdll=pthrdrtl -I../include -I../regex -I.. \
-o example udf_example.cc -L../lib -lmysqlclient udf_example.def
mv example.dll example.udf
Note: Due to limitations in OS/2, UDF module name stems must not
exceed 8 characters. Modules are stored in the `/mysql2/udf'
directory; the safe-mysqld.cmd script will put this directory in
the BEGINLIBPATH environment variable. When using UDF modules,
specified extensions are ignored@-it is assumed to be `.udf'.
For example, in Unix, the shared module might be named `example.so'
and you would load a function from it like this:
mysql> CREATE FUNCTION metaphon RETURNS STRING SONAME "example.so";
Is OS/2, the module would be named `example.udf', but you would not specify the module extension:
mysql> CREATE FUNCTION metaphon RETURNS STRING SONAME "example";
We are really interested in getting MySQL to work on BeOS, but unfortunately we don't have any person who knows BeOS or has time to do a port.
We are interested in finding someone to do a port, and we will help them with any technical questions they may have while doing the port.
We have previously talked with some BeOS developers that have said that MySQL is 80% ported to BeOS, but we haven't heard from them in a while.
We are really interested in getting MySQL to work on NetWare, but unfortunately we don't have any person who knows NetWare or has time to do a port.
We are interested in finding someone to do a port, and we will help them with any technical questions they may have while doing the port.
Perl support for MySQL is provided by means of the
DBI/DBD client interface. See section 8.2 MySQL Perl API. The Perl
DBD/DBI client code requires Perl Version 5.004 or later. The
interface will not work if you have an older version of Perl.
MySQL Perl support also requires that you've installed MySQL client programming support. If you installed MySQL from RPM files, client programs are in the client RPM, but client programming support is in the developer RPM. Make sure you've installed the latter RPM.
As of Version 3.22.8, Perl support is distributed separately from the main MySQL distribution. If you want to install Perl support, the files you will need can be obtained from http://www.mysql.com/downloads/api-dbi.html.
The Perl distributions are provided as compressed tar archives and
have names like `MODULE-VERSION.tar.gz', where MODULE is the
module name and VERSION is the version number. You should get the
Data-Dumper, DBI, and Msql-Mysql-modules distributions
and install them in that order. The installation procedure is shown here.
The example shown is for the Data-Dumper module, but the procedure is
the same for all three distributions:
shell> gunzip < Data-Dumper-VERSION.tar.gz | tar xvf -This command creates a directory named `Data-Dumper-VERSION'.
shell> cd Data-Dumper-VERSION
shell> perl Makefile.PL shell> make shell> make test shell> make install
The make test command is important because it verifies that the
module is working. Note that when you run that command during the
Msql-Mysql-modules installation to exercise the interface code, the
MySQL server must be running or the test will fail.
It is a good idea to rebuild and reinstall the Msql-Mysql-modules
distribution whenever you install a new release of MySQL,
particularly if you notice symptoms such as all your DBI scripts
dumping core after you upgrade MySQL.
If you don't have the right to install Perl modules in the system directory or if you to install local Perl modules, the following reference may help you:
http://www.iserver.com/support/contrib/perl5/modules.html
Look under the heading
Installing New Modules that Require Locally Installed Modules.
To install the MySQL DBD module with ActiveState Perl on
Windows, you should do the following:
set HTTP_proxy=my.proxy.com:3128
C:\> c:\perl\bin\ppm.pl
DBI:
ppm> install DBI
install \ ftp://ftp.de.uu.net/pub/CPAN/authors/id/JWIED/DBD-mysql-1.2212.x86.ppd
The above should work at least with ActiveState Perl Version 5.6.
If you can't get the above to work, you should instead install the
MyODBC driver and connect to MySQL server through
ODBC:
use DBI;
$dbh= DBI->connect("DBI:ODBC:$dsn","$user","$password") ||
die "Got error $DBI::errstr when connecting to $dsn\n";
The MySQL Perl distribution contains DBI,
DBD:MySQL and DBD:ODBC.
C: so that you get a `C:\PERL' directory.
perl works by executing perl -v in a DOS shell.
DBI/DBD InterfaceIf Perl reports that it can't find the `../mysql/mysql.so' module, then the problem is probably that Perl can't locate the shared library `libmysqlclient.so'.
You can fix this by any of the following methods:
Msql-Mysql-modules distribution with perl
Makefile.PL -static -config rather than perl Makefile.PL.
LD_RUN_PATH environment variable.
If you get the following errors from DBD-mysql,
you are probably using gcc (or using an old binary compiled with
gcc):
/usr/bin/perl: can't resolve symbol '__moddi3' /usr/bin/perl: can't resolve symbol '__divdi3'
Add -L/usr/lib/gcc-lib/... -lgcc to the link command when the
`mysql.so' library gets built (check the output from make for
`mysql.so' when you compile the Perl client). The -L option
should specify the pathname of the directory where `libgcc.a' is located
on your system.
Another cause of this problem may be that Perl and MySQL aren't both
compiled with gcc. In this case, you can solve the mismatch by
compiling both with gcc.
If you get the following error from Msql-Mysql-modules
when you run the tests:
t/00base............install_driver(mysql) failed: Can't load '../blib/arch/auto/DBD/mysql/mysql.so' for module DBD::mysql: ../blib/arch/auto/DBD/mysql/mysql.so: undefined symbol: uncompress at /usr/lib/perl5/5.00503/i586-linux/DynaLoader.pm line 169.
it means that you need to include the compression library, -lz, to the link line. This can be doing the following change in the file `lib/DBD/mysql/Install.pm':
$sysliblist .= " -lm"; to $sysliblist .= " -lm -lz";
After this, you must run 'make realclean' and then proceed with the installation from the beginning.
If you want to use the Perl module on a system that doesn't support
dynamic linking (like Caldera/SCO) you can generate a static version of
Perl that includes DBI and DBD-mysql. The way this works
is that you generate a version of Perl with the DBI code linked
in and install it on top of your current Perl. Then you use that to
build a version of Perl that additionally has the DBD code linked
in, and install that.
On Caldera (SCO), you must have the following environment variables set:
shell> LD_LIBRARY_PATH=/lib:/usr/lib:/usr/local/lib:/usr/progressive/lib or shell> LD_LIBRARY_PATH=/usr/lib:/lib:/usr/local/lib:/usr/ccs/lib:\ /usr/progressive/lib:/usr/skunk/lib shell> LIBPATH=/usr/lib:/lib:/usr/local/lib:/usr/ccs/lib:\ /usr/progressive/lib:/usr/skunk/lib shell> MANPATH=scohelp:/usr/man:/usr/local1/man:/usr/local/man:\ /usr/skunk/man:
First, create a Perl that includes a statically linked DBI by running
these commands in the directory where your DBI distribution is
located:
shell> perl Makefile.PL -static -config shell> make shell> make install shell> make perl
Then you must install the new Perl. The output of make perl will
indicate the exact make command you will need to execute to perform
the installation. On Caldera (SCO), this is
make -f Makefile.aperl inst_perl MAP_TARGET=perl.
Next, use the just-created Perl to create another Perl that also includes a
statically-linked DBD::mysql by running these commands in the
directory where your Msql-Mysql-modules distribution is located:
shell> perl Makefile.PL -static -config shell> make shell> make install shell> make perl
Finally, you should install this new Perl. Again, the output of make
perl indicates the command to use.
This chapter provides a tutorial introduction to MySQL by showing
how to use the mysql client program to create and use a simple
database. mysql (sometimes referred to as the ``terminal monitor'' or
just ``monitor'') is an interactive program that allows you to connect to a
MySQL server, run queries, and view the results. mysql may
also be used in batch mode: you place your queries in a file beforehand, then
tell mysql to execute the contents of the file. Both ways of using
mysql are covered here.
To see a list of options provided by mysql, invoke it with
the --help option:
shell> mysql --help
This chapter assumes that mysql is installed on your machine and that
a MySQL server is available to which you can connect. If this is
not true, contact your MySQL administrator. (If you are the
administrator, you will need to consult other sections of this manual.)
This chapter describes the entire process of setting up and using a database. If you are interested only in accessing an already-existing database, you may want to skip over the sections that describe how to create the database and the tables it contains.
Because this chapter is tutorial in nature, many details are necessarily left out. Consult the relevant sections of the manual for more information on the topics covered here.
To connect to the server, you'll usually need to provide a MySQL
user name when you invoke mysql and, most likely, a password. If the
server runs on a machine other than the one where you log in, you'll also
need to specify a hostname. Contact your administrator to find out what
connection parameters you should use to connect (that is, what host, user name,
and password to use). Once you know the proper parameters, you should be
able to connect like this:
shell> mysql -h host -u user -p Enter password: ********
The ******** represents your password; enter it when mysql
displays the Enter password: prompt.
If that works, you should see some introductory information followed by a
mysql> prompt:
shell> mysql -h host -u user -p Enter password: ******** Welcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 459 to server version: 3.22.20a-log Type 'help' for help. mysql>
The prompt tells you that mysql is ready for you to enter commands.
Some MySQL installations allow users to connect as the anonymous
(unnamed) user to the server running on the local host. If this is the case
on your machine, you should be able to connect to that server by invoking
mysql without any options:
shell> mysql
After you have connected successfully, you can disconnect any time by typing
QUIT at the mysql> prompt:
mysql> QUIT Bye
You can also disconnect by pressing Control-D.
Most examples in the following sections assume you are connected to the
server. They indicate this by the mysql> prompt.
Make sure you are connected to the server, as discussed in the previous
section. Doing so will not in itself select any database to work with, but
that's okay. At this point, it's more important to find out a little about
how to issue queries than to jump right in creating tables, loading data
into them, and retrieving data from them. This section describes the basic
principles of entering commands, using several queries you can try out to
familiarise yourself with how mysql works.
Here's a simple command that asks the server to tell you its version number
and the current date. Type it in as shown here following the mysql>
prompt and press Enter:
mysql> SELECT VERSION(), CURRENT_DATE; +--------------+--------------+ | VERSION() | CURRENT_DATE | +--------------+--------------+ | 3.22.20a-log | 1999-03-19 | +--------------+--------------+ 1 row in set (0.01 sec) mysql>
This query illustrates several things about mysql:
QUIT,
mentioned earlier, is one of them. We'll get to others later.)
mysql sends it to the server for execution
and displays the results, then prints another mysql> to indicate
that it is ready for another command.
mysql displays query output as a table (rows and columns). The first
row contains labels for the columns. The rows following are the query
results. Normally, column labels are the names of the columns you fetch from
database tables. If you're retrieving the value of an expression rather than
a table column (as in the example just shown), mysql labels the column
using the expression itself.
mysql shows how many rows were returned and how long the query took
to execute, which gives you a rough idea of server performance. These values
are imprecise because they represent wall clock time (not CPU or machine
time), and because they are affected by factors such as server load and
network latency. (For brevity, the ``rows in set'' line is not shown in
the remaining examples in this chapter.)
Keywords may be entered in any lettercase. The following queries are equivalent:
mysql> SELECT VERSION(), CURRENT_DATE; mysql> select version(), current_date; mysql> SeLeCt vErSiOn(), current_DATE;
Here's another query. It demonstrates that you can use mysql as a
simple calculator:
mysql> SELECT SIN(PI()/4), (4+1)*5; +-------------+---------+ | SIN(PI()/4) | (4+1)*5 | +-------------+---------+ | 0.707107 | 25 | +-------------+---------+
The commands shown thus far have been relatively short, single-line statements. You can even enter multiple statements on a single line. Just end each one with a semicolon:
mysql> SELECT VERSION(); SELECT NOW(); +--------------+ | VERSION() | +--------------+ | 3.22.20a-log | +--------------+ +---------------------+ | NOW() | +---------------------+ | 1999-03-19 00:15:33 | +---------------------+
A command need not be given all on a single line, so lengthy commands that
require several lines are not a problem. mysql determines where your
statement ends by looking for the terminating semicolon, not by looking for
the end of the input line. (In other words, mysql
accepts free-format input: it collects input lines but does not execute them
until it sees the semicolon.)
Here's a simple multiple-line statement:
mysql> SELECT
-> USER()
-> ,
-> CURRENT_DATE;
+--------------------+--------------+
| USER() | CURRENT_DATE |
+--------------------+--------------+
| joesmith@localhost | 1999-03-18 |
+--------------------+--------------+
In this example, notice how the prompt changes from mysql> to
-> after you enter the first line of a multiple-line query. This is
how mysql indicates that it hasn't seen a complete statement and is
waiting for the rest. The prompt is your friend, because it provides
valuable feedback. If you use that feedback, you will always be aware of
what mysql is waiting for.
If you decide you don't want to execute a command that you are in the
process of entering, cancel it by typing \c:
mysql> SELECT
-> USER()
-> \c
mysql>
Here, too, notice the prompt. It switches back to mysql> after you
type \c, providing feedback to indicate that mysql is ready
for a new command.
The following table shows each of the prompts you may see and summarises what
they mean about the state that mysql is in:
| Prompt | Meaning |
mysql> | Ready for new command. |
-> | Waiting for next line of multiple-line command. |
'> | Waiting for next line, collecting a string that begins with a single quote (`''). |
"> | Waiting for next line, collecting a string that begins with a double quote (`"'). |
Multiple-line statements commonly occur by accident when you intend to
issue a command on a single line, but forget the terminating semicolon. In
this case, mysql waits for more input:
mysql> SELECT USER()
->
If this happens to you (you think you've entered a statement but the only
response is a -> prompt), most likely mysql is waiting for the
semicolon. If you don't notice what the prompt is telling you, you might sit
there for a while before realising what you need to do. Enter a semicolon to
complete the statement, and mysql will execute it:
mysql> SELECT USER()
-> ;
+--------------------+
| USER() |
+--------------------+
| joesmith@localhost |
+--------------------+
The '> and "> prompts occur during string collection.
In MySQL, you can write strings surrounded by either `''
or `"' characters (for example, 'hello' or "goodbye"),
and mysql lets you enter strings that span multiple lines. When you
see a '> or "> prompt, it means that you've entered a line
containing a string that begins with a `'' or `"' quote character,
but have not yet entered the matching quote that terminates the string.
That's fine if you really are entering a multiple-line string, but how likely
is that? Not very. More often, the '> and "> prompts indicate
that you've inadvertantly left out a quote character. For example:
mysql> SELECT * FROM my_table WHERE name = "Smith AND age < 30;
">
If you enter this SELECT statement, then press Enter and wait for the
result, nothing will happen. Instead of wondering why this
query takes so long, notice the clue provided by the "> prompt. It
tells you that mysql expects to see the rest of an unterminated
string. (Do you see the error in the statement? The string "Smith is
missing the second quote.)
At this point, what do you do? The simplest thing is to cancel the command.
However, you cannot just type \c in this case, because mysql
interprets it as part of the string that it is collecting! Instead, enter
the closing quote character (so mysql knows you've finished the
string), then type \c:
mysql> SELECT * FROM my_table WHERE name = "Smith AND age < 30;
"> "\c
mysql>
The prompt changes back to mysql>, indicating that mysql
is ready for a new command.
It's important to know what the '> and "> prompts signify,
because if you mistakenly enter an unterminated string, any further lines you
type will appear to be ignored by mysql@-including a line
containing QUIT! This can be quite confusing, especially if you
don't know that you need to supply the terminating quote before you can
cancel the current command.
Now that you know how to enter commands, it's time to access a database.
Suppose you have several pets in your home (your menagerie) and you'd like to keep track of various types of information about them. You can do so by creating tables to hold your data and loading them with the desired information. Then you can answer different sorts of questions about your animals by retrieving data from the tables. This section shows you how to:
The menagerie database will be simple (deliberately), but it is not difficult
to think of real-world situations in which a similar type of database might
be used. For example, a database like this could be used by a farmer to keep
track of livestock, or by a veterinarian to keep track of patient records.
A menagerie distribution containing some of the queries and sample data used
in the following sections can be obtained from the MySQL web site.
It's available in either compressed tar format
(http://www.mysql.com/Downloads/Contrib/Examples/menagerie.tar.gz)
or Zip format
(http://www.mysql.com/Downloads/Contrib/Examples/menagerie.zip).
Use the SHOW statement to find out what databases currently exist
on the server:
mysql> SHOW DATABASES; +----------+ | Database | +----------+ | mysql | | test | | tmp | +----------+
The list of databases is probably different on your machine, but the
mysql and test databases are likely to be among them. The
mysql database is required because it describes user access
privileges. The test database is often provided as a workspace for
users to try things out.
Note that you may not see all databases if you don't have the
SHOW DATABASES privilege. See section 4.3.1 GRANT and REVOKE Syntax.
If the test database exists, try to access it:
mysql> USE test Database changed
Note that USE, like QUIT, does not require a semicolon. (You
can terminate such statements with a semicolon if you like; it does no harm.)
The USE statement is special in another way, too: it must be given on
a single line.
You can use the test database (if you have access to it) for the
examples that follow, but anything you create in that database can be
removed by anyone else with access to it. For this reason, you should
probably ask your MySQL administrator for permission to use a
database of your own. Suppose you want to call yours menagerie. The
administrator needs to execute a command like this:
mysql> GRANT ALL ON menagerie.* TO your_mysql_name;
where your_mysql_name is the MySQL user name assigned to
you.
If the administrator creates your database for you when setting up your permissions, you can begin using it. Otherwise, you need to create it yourself:
mysql> CREATE DATABASE menagerie;
Under Unix, database names are case-sensitive (unlike SQL keywords), so you
must always refer to your database as menagerie, not as
Menagerie, MENAGERIE, or some other variant. This is also true
for table names. (Under Windows, this restriction does not apply, although
you must refer to databases and tables using the same lettercase throughout a
given query.)
Creating a database does not select it for use; you must do that explicitly.
To make menagerie the current database, use this command:
mysql> USE menagerie Database changed
Your database needs to be created only once, but you must select it for use
each time you begin a mysql session. You can do this by issuing a
USE statement as shown above. Alternatively, you can select the
database on the command-line when you invoke mysql. Just specify its
name after any connection parameters that you might need to provide. For
example:
shell> mysql -h host -u user -p menagerie Enter password: ********
Note that menagerie is not your password on the command just shown.
If you want to supply your password on the command-line after the -p
option, you must do so with no intervening space (for example, as
-pmypassword, not as -p mypassword). However, putting your
password on the command-line is not recommended, because doing so exposes it
to snooping by other users logged in on your machine.
Creating the database is the easy part, but at this point it's empty, as
SHOW TABLES will tell you:
mysql> SHOW TABLES; Empty set (0.00 sec)
The harder part is deciding what the structure of your database should be: what tables you will need and what columns will be in each of them.
You'll want a table that contains a record for each of your pets. This can
be called the pet table, and it should contain, as a bare minimum,
each animal's name. Because the name by itself is not very interesting, the
table should contain other information. For example, if more than one person
in your family keeps pets, you might want to list each animal's owner. You
might also want to record some basic descriptive information such as species
and sex.
How about age? That might be of interest, but it's not a good thing to store in a database. Age changes as time passes, which means you'd have to update your records often. Instead, it's better to store a fixed value such as date of birth. Then, whenever you need age, you can calculate it as the difference between the current date and the birth date. MySQL provides functions for doing date arithmetic, so this is not difficult. Storing birth date rather than age has other advantages, too:
You can probably think of other types of information that would be useful in
the pet table, but the ones identified so far are sufficient for now:
name, owner, species, sex, birth, and death.
Use a CREATE TABLE statement to specify the layout of your table:
mysql> CREATE TABLE pet (name VARCHAR(20), owner VARCHAR(20),
-> species VARCHAR(20), sex CHAR(1), birth DATE, death DATE);
VARCHAR is a good choice for the name, owner, and
species columns because the column values will vary in length. The
lengths of those columns need not all be the same, and need not be
20. You can pick any length from 1 to 255, whatever
seems most reasonable to you. (If you make a poor choice and it turns
out later that you need a longer field, MySQL provides an
ALTER TABLE statement.)
Several types of values can be chosen to represent sex in animal records,
such as "m"
and "f", or perhaps "male" and "female". It's simplest
to use the single characters "m" and "f".
The use of the DATE data type for the birth and death
columns is a fairly obvious choice.
Now that you have created a table, SHOW TABLES should produce some
output:
mysql> SHOW TABLES; +---------------------+ | Tables in menagerie | +---------------------+ | pet | +---------------------+
To verify that your table was created the way you expected, use
a DESCRIBE statement:
mysql> DESCRIBE pet; +---------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +---------+-------------+------+-----+---------+-------+ | name | varchar(20) | YES | | NULL | | | owner | varchar(20) | YES | | NULL | | | species | varchar(20) | YES | | NULL | | | sex | char(1) | YES | | NULL | | | birth | date | YES | | NULL | | | death | date | YES | | NULL | | +---------+-------------+------+-----+---------+-------+
You can use DESCRIBE any time, for example, if you forget the names of
the columns in your table or what types they are.
After creating your table, you need to populate it. The LOAD DATA and
INSERT statements are useful for this.
Suppose your pet records can be described as shown here.
(Observe that MySQL expects dates in 'YYYY-MM-DD' format;
this may be different from what you are used to.)
| name | owner | species | sex | birth | death |
| Fluffy | Harold | cat | f | 1993-02-04 | |
| Claws | Gwen | cat | m | 1994-03-17 | |
| Buffy | Harold | dog | f | 1989-05-13 | |
| Fang | Benny | dog | m | 1990-08-27 | |
| Bowser | Diane | dog | m | 1998-08-31 | 1995-07-29 |
| Chirpy | Gwen | bird | f | 1998-09-11 | |
| Whistler | Gwen | bird | 1997-12-09 | ||
| Slim | Benny | snake | m | 1996-04-29 |
Because you are beginning with an empty table, an easy way to populate it is to create a text file containing a row for each of your animals, then load the contents of the file into the table with a single statement.
You could create a text file `pet.txt' containing one record per line,
with values separated by tabs, and given in the order in which the columns
were listed in the CREATE TABLE statement. For missing values (such
as unknown sexes or death dates for animals that are still living), you can
use NULL values. To represent these in your text file, use
\N. For example, the record for Whistler the bird would look like
this (where the whitespace between values is a single tab character):
| name | owner | species | sex | birth | death |
Whistler | Gwen | bird | \N | 1997-12-09 | \N
|
To load the text file `pet.txt' into the pet table, use this
command:
mysql> LOAD DATA LOCAL INFILE "pet.txt" INTO TABLE pet;
You can specify the column value separator and end of line marker explicitly
in the LOAD DATA statement if you wish, but the defaults are tab and
linefeed. These are sufficient for the statement to read the file
`pet.txt' properly.
When you want to add new records one at a time, the INSERT statement
is useful. In its simplest form, you supply values for each column, in the
order in which the columns were listed in the CREATE TABLE statement.
Suppose Diane gets a new hamster named Puffball. You could add a new record
using an INSERT statement like this:
mysql> INSERT INTO pet
-> VALUES ('Puffball','Diane','hamster','f','1999-03-30',NULL);
Note that string and date values are specified as quoted strings here. Also,
with INSERT, you can insert NULL directly to represent a
missing value. You do not use \N like you do with LOAD DATA.
From this example, you should be able to see that there would be a lot more
typing involved to load
your records initially using several INSERT statements rather
than a single LOAD DATA statement.
The SELECT statement is used to pull information from a table.
The general form of the statement is:
SELECT what_to_select FROM which_table WHERE conditions_to_satisfy
what_to_select indicates what you want to see. This can be a list of
columns, or * to indicate ``all columns.'' which_table
indicates the table from which you want to retrieve data. The WHERE
clause is optional. If it's present, conditions_to_satisfy specifies
conditions that rows must satisfy to qualify for retrieval.
The simplest form of SELECT retrieves everything from a table:
mysql> SELECT * FROM pet; +----------+--------+---------+------+------------+------------+ | name | owner | species | sex | birth | death | +----------+--------+---------+------+------------+------------+ | Fluffy | Harold | cat | f | 1993-02-04 | NULL | | Claws | Gwen | cat | m | 1994-03-17 | NULL | | Buffy | Harold | dog | f | 1989-05-13 | NULL | | Fang | Benny | dog | m | 1990-08-27 | NULL | | Bowser | Diane | dog | m | 1998-08-31 | 1995-07-29 | | Chirpy | Gwen | bird | f | 1998-09-11 | NULL | | Whistler | Gwen | bird | NULL | 1997-12-09 | NULL | | Slim | Benny | snake | m | 1996-04-29 | NULL | | Puffball | Diane | hamster | f | 1999-03-30 | NULL | +----------+--------+---------+------+------------+------------+
This form of SELECT is useful if you want to review your entire table,
for instance, after you've just loaded it with your initial dataset. As it
happens, the output just shown reveals an error in your datafile: Bowser
appears to have been born after he died! Consulting your original pedigree
papers, you find that the correct birth year is 1989, not 1998.
There are least a couple of ways to fix this:
DELETE and LOAD DATA:
mys