MySQL Reference Manual for version 3.23.41.

1 General Information About MySQL

This is the MySQL reference manual; it documents MySQL Version 3.23.41. As MySQL is work in progress, the manual gets updated frequently. There is a very good chance that this version is out of date, unless you are looking at it online. The most recent version of this manual is available at http://www.mysql.com/documentation/ in many different formats. If you have a hard time finding information in the manual, you can try the searchable PHP version at http://www.mysql.com/documentation/manual.php.

MySQL is a very fast, multi-threaded, multi-user, and robust SQL (Structured Query Language) database server.

MySQL is free software. It is licensed with the GNU GENERAL PUBLIC LICENSE http://www.gnu.org/. See section 1.3 MySQL Licensing and Support.

The MySQL home page provides the latest information about MySQL.

The following list describes some useful sections of the manual:

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 1.2.22.3 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. If you have found a sensitive security bug in MySQL, you should send an email to security@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.

This is a reference manual; it does not provide general instruction on SQL or relational database concepts. If you want general information about SQL, see section 1.2.2 General SQL Information and Tutorials. For books that focus more specifically on MySQL, see section 1.2.1 Books About MySQL.

1.1 MySQL, MySQL AB, and Open Source

1.1.1 What Is MySQL

MySQL, the most popular Open Source SQL database, is provided by MySQL AB. MySQL AB is a commercial company that builds its business providing services around the MySQL database. See section 1.1.2 What Is MySQL AB.

MySQL is a database management system.
A database is a structured collection of data. It may be anything from a simple shopping list to a picture gallery or the vast amounts of information in a corporate network. To add, access, and process data stored in a computer database, you need a database management system such as MySQL. 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.
MySQL is a relational database management system.
A relational database stores data in separate tables rather than putting all the data in one big storeroom. This adds speed and flexibility. The tables are linked by defined relations making it possible to combine data from several tables on request. The SQL part of MySQL stands for "Structured Query Language" - the most common standardized language used to access databases.
MySQL is Open Source Software.
Open Source means that it is possible for anyone to use and modify. Anybody can download MySQL from the Internet and use it without paying anything. Anybody so inclined can study the source code and change it to fit their needs. MySQL uses the GPL (GNU General Public License) http://www.gnu.org, 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 into a commercial application you can buy a commercially licensed version from us.
Why use MySQL?
MySQL is very fast, reliable, and easy to use. If that is what you are looking for, you should give it a try. MySQL also has a very practical set of features developed in very close cooperation with our users. You can find a performance comparison of MySQL to some other database managers on our benchmark page. See section 5.1.4 The MySQL Benchmark Suite. MySQL was originally developed to handle very 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 today offers a rich and very useful set of functions. The connectivity, speed, and security make MySQL highly suited for accessing databases on the Internet.
The technical features of MySQL
For advanced technical information, see section 6 MySQL Language Reference. MySQL 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 several programming interfaces. We also provide MySQL as a multi-threaded library which you can link into your application to get a smaller, faster, easier to manage product.
MySQL has a lot of contributed software available.
It is very likely that you will find that your favorite application or language already supports MySQL.

The official way to pronounce MySQL is ``My Ess Que Ell'' (not MY-SEQUEL). But we try to avoid correcting people who say MY-SEQUEL.

1.1.2 What Is MySQL AB

MySQL AB is the Swedish company owned and run by the MySQL founders and main developers. We are dedicated to developing MySQL and spreading our database to new users. MySQL AB owns the copyright to the MySQL server source code and the MySQL trademark. A significant amount of revenues from our services goes to developing MySQL. See section 1.1.1 What Is MySQL.

MySQL AB has been profitable providing MySQL from the start. We don't get any outside funding, but have earned all our money ourselves.

We are searching after partners that would like to support our development of MySQL so that we could accelerate the development pace. If you are interested in doing this, you can email partner@mysql.com about this!

MySQL AB has currently 20+ people (http://www.mysql.com/development/team.html) on its payroll and is growing rapidly.

Our main sources of income are:

The MySQL core values show our dedication to MySQL and Open Source.

We want MySQL to be:

MySQL AB and the people of MySQL AB:

1.1.3 About This Manual

This manual is currently available in Texinfo, plain text, Info, HTML, PostScript, and PDF 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.

This manual is written and maintained by David Axmark, Michael (Monty) Widenius, Jeremy Cole, and Paul DuBois. For other contributors, see section F Credits.

1.1.4 Conventions Used in This Manual

This manual uses certain typographical conventions:

constant
Constant-width font is used for command names and options; SQL statements; database, table and column names; C and Perl code; and environment variables. Example: ``To see how mysqladmin works, invoke it with the --help option.''
`filename'
Constant-width font with surrounding quotes is used for filenames and pathnames. Example: ``The distribution is installed under the `/usr/local/' directory.''
`c'
Constant-width font with surrounding quotes is also used to indicate character sequences. Example: ``To specify a wild card, use the `%' character.''
italic
Italic font is used for emphasis, like this.
boldface
Boldface font is used for access privilege names (for example, ``do not grant the process privilege lightly'') and occasionally to convey especially strong emphasis.

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 statements may be written in uppercase or lowercase. When this manual shows a SQL statement, uppercase is used for particular keywords if those keywords are under discussion (to emphasize them) and lowercase is used for the rest of the statement. For example, you might see the following in a discussion of the SELECT statement: 

mysql> SELECT count(*) FROM tbl_name;

On the other hand, in a discussion of the COUNT() function, the same statement would be written like this: 

mysql> select COUNT(*) from tbl_name;

If no particular emphasis is intended, all keywords are written uniformly in uppercase.

In syntax descriptions, square brackets (`[' and `]') are used to indicate optional words or clauses: 

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}

1.1.5 History of MySQL

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.

1.1.6 The Main Features of MySQL

The following list describes some of the important characteristics of MySQL:

1.1.7 How Stable Is MySQL?

This section addresses the questions ``How stable is MySQL?'' and ``Can I depend on MySQL in this project?'' We will try to clarify some issues and to answer some of the more important questions that seem to concern many people. This section has been put together from information gathered from the mailing list (which is very active in reporting bugs).

At TcX, MySQL has worked without any problems in our projects since mid-1996. When MySQL 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 queries in a manner different than our own. Each new release has had fewer portability problems than the previous one (even though each has had many new features).

Each release of MySQL has been usable, and there have been problems only when users start to use code from the ``gray zones.'' Naturally, outside users don't know what the gray zones are; this section attempts to indicate those that are currently known. The descriptions deal with Version 3.23 of MySQL. All known and reported bugs are fixed in the latest version, with the exception of the bugs listed in the bugs section, which are things that are design-related. See section 1.4.7 Known errors and design deficiencies in MySQL.

MySQL is written in multiple layers and different independent modules. These modules are listed below with an indication of how well-tested each of them is:

The ISAM table handler -- Stable
This manages storage and retrieval of all data in MySQL Version 3.22 and earlier. In all MySQL releases there hasn't been a single (reported) bug in this code. The only known way to get a corrupted table is to kill the server in the middle of an update. Even that is unlikely to destroy any data beyond rescue, because all data are flushed to disk between each query. There hasn't been a single bug report about lost data because of bugs in MySQL.
The MyISAM table handler -- Stable
This is new in MySQL Version 3.23. It's largely based on the ISAM table code but has a lot of new and very useful features.
The parser and lexical analyser -- Stable
There hasn't been a single reported bug in this system for a long time.
The C client code -- Stable
No known problems. In early Version 3.20 releases, there were some limitations in the send/receive buffer size. As of Version 3.21, the buffer size is now dynamic up to a default of 16M.
Standard client programs -- Stable
These include mysql, mysqladmin, mysqlshow, mysqldump, and mysqlimport.
Basic SQL -- Stable
The basic SQL function system and string classes and dynamic memory handling. Not a single reported bug in this system.
Query optimizer -- Stable
Range optimizer -- Stable
Join optimizer -- Stable
Locking -- Gamma
This is very system-dependent. On some systems there are big problems using standard OS locking (fcntl()). In these cases, you should run the MySQL daemon with the --skip-locking flag. Problems are known to occur on some Linux systems, and on SunOS when using NFS-mounted file systems.
Linux threads -- Stable
The major problem found has been with the fcntl() call, which is fixed by using the --skip-locking option to mysqld. Some people have reported lockup problems with Version 0.5. LinuxThreads will need to be recompiled if you plan to use 1000+ concurrent connections. Although it is possible to run that many connections with the default LinuxThreads (however, you will never go above 1021), the default stack spacing of 2 MB makes the application unstable, and we have been able to reproduce a coredump after creating 1021 idle connections. See section 2.6.1 Linux Notes (All Linux Versions).
Solaris 2.5+ pthreads -- Stable
We use this for all our production work.
MIT-pthreads (Other systems) -- Stable
There have been no reported bugs since Version 3.20.15 and no known bugs since Version 3.20.16. On some systems, there is a ``misfeature'' where some operations are quite slow (a 1/20 second sleep is done between each query). Of course, MIT-pthreads may slow down everything a bit, but index-based SELECT statements are usually done in one time frame so there shouldn't be a mutex locking/thread juggling.
Other thread implementions -- Beta - Gamma
The ports to other systems are still very new and may have bugs, possibly in MySQL, but most often in the thread implementation itself.
LOAD DATA ..., INSERT ... SELECT -- Stable
Some people thought they had found bugs here, but these usually have turned out to be misunderstandings. Please check the manual before reporting problems!
ALTER TABLE -- Stable
Small changes in Version 3.22.12.
DBD -- Stable
Now maintained by Jochen Wiedmann (wiedmann@neckar-alb.de). Thanks!
mysqlaccess -- Stable
Written and maintained by Yves Carlier (Yves.Carlier@rug.ac.be). Thanks!
GRANT -- Stable
Big changes made in MySQL Version 3.22.12.
MyODBC (uses ODBC SDK 2.5) -- Gamma
It seems to work well with some programs.
Replication -- Beta / Gamma
We are still working on replication, so don't expect this to be rock solid yet. On the other hand, some MySQL users are already using this with good results.
BDB Tables -- Beta
The Berkeley DB code is very stable, but we are still improving the interface between MySQL and BDB tables, so it will take some time before this is as tested as the other table types.
InnoDB Tables -- Beta
This is a recent addition to MySQL. They appear to work good and can be used after some initial testing.
Automatic recovery of MyISAM tables - Beta
This only affects the new code that checks if the table was closed properly on open and executes an automatic check/repair of the table if it wasn't.
MERGE tables -- Beta / Gamma
The usage of keys on MERGE tables is still not that tested. The other part of the MERGE code is quite well tested.
FULLTEXT -- Beta
Text search seems to work, but is still not widely used.

MySQL AB provides e-mail 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.

1.1.8 How Big Can MySQL Tables Be?

MySQL Version 3.22 has a 4G limit on table size. With the new MyISAM 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
Solaris 2.7 Intel 4G
Solaris 2.7 ULTRA-SPARC 8T (?)

On Linux 2.2 you can get bigger tables than 2G by using the LFS patch for the ext2 file system. On Linux 2.4 there exists also patches for ReiserFS to get support for big files.

This means that the table size for MySQL 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 4.5.5 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.

1.1.9 Year 2000 Compliance

MySQL itself has no problems with Year 2000 (Y2K) compliance:

You may run into problems with applications that use MySQL 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 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 is Y2K-compliant, it is your responsibility to provide unambiguous input. See section 6.2.2.1 Y2K Issues and Date Types for MySQL's rules for dealing with ambiguous date input data (data containing 2-digit year values).

1.2 MySQL Information Sources

1.2.1 Books About MySQL

While this manual is still the right place for up to date technical information, its primary goal is to contain everything there is to know about MySQL. It is sometimes nice to have a bound book to read in bed or while you travel. Here is a list of books about MySQL and related subjects (in English).

By purchasing a book through these hyperlinks provided herein, you are contributing to the development of MySQL.

MySQL
Available Barnes and Noble
Publisher New Riders
Author Paul DuBois
Pub Date 1st Edition December 1999
ISBN 0735709211
Pages 800
Price $49.99 US
Downloadable examples samp_db distribution
Errata are available here

Foreword by Michael ``Monty'' Widenius, MySQL Moderator.

In MySQL, Paul DuBois provides you with a comprehensive guide to one of the most popular relational database systems. Paul has contributed to the online documentation for MySQL and is an active member of the MySQL community. The principal MySQL developer, Monty Widenius, and a network of his fellow developers reviewed the manuscript, and provided Paul with the kind of insight no one else could supply.

Instead of merely giving you a general overview of MySQL, Paul teaches you how to make the most of its capabilities. Through two sample database applications that run throughout the book, he gives you solutions to problems you're sure to face. He helps you integrate MySQL efficiently with third-party tools, such as PHP and Perl, enabling you to generate dynamic Web pages through database queries. He teaches you to write programs that access MySQL databases, and also provides a comprehensive set of references to column types, operators, functions, SQL syntax, MySQL programming, C API, Perl DBI, and PHP API. MySQL simply gives you the kind of information you won't find anywhere else.

If you use MySQL, this book provides you with:


MySQL & mSQL
Available Barnes and Noble
Publisher O'Reilly
Authors Randy Jay Yarger, George Reese & Tim King
Pub Date 1st Edition July 1999
ISBN 1-56592-434-7, Order Number: 4347
Pages 506
Price $34.95

This book teaches you how to use MySQL and mSQL, two popular and robust database products that support key subsets of SQL on both Linux and Unix systems. Anyone who knows basic C, Java, Perl, or Python can write a program to interact with a database, either as a stand-alone application or through a Web page. This book takes you through the whole process, from installation and configuration to programming interfaces and basic administration. Includes plenty of tutorial material.

Sams' Teach Yourself MySQL in 21 Days
Available Barnes and Noble
Publisher Sams
Authors Mark Maslakowski and Tony Butcher
Pub Date June 2000
ISBN 0672319144
Pages 650
Price $39.99

Sams' Teach Yourself MySQL in 21 Days is for intermediate Linux users who want to move into databases. A large share of the audience is Web developers who need a database to store large amounts of information that can be retrieved via the Web.

Sams' Teach Yourself MySQL in 21 Days is a practical, step-by-step tutorial. The reader will learn to design and employ this open source database technology into his or her Web site using practical, hands-on examples to follow.

E-Commerce Solutions with MySQL
Available Barnes and Noble
Publisher Prima Communications, Inc.
Authors N/A
Pub Date January 2000
ISBN 0761524452
Pages 500
Price $39.99

No description available.

MySQL and PHP from Scratch
Available Barnes and Noble
Publisher Que
Authors N/A
Pub Date September 2000
ISBN 0789724405
Pages 550
Price $34.99

This book puts together information on installing, setting up, and troubleshooting Apache, MySQL, PHP3, and IMP into one complete volume. You also learn how each piece is part of a whole by learning, step-by-step, how to create a web-based e-mail system. Learn to run the equivalent of Active Server Pages (ASP) using PHP3, set up an e-commerce site using a database and the Apache web server, and create a data entry system (such as sales, product quality tracking, customer preferences, etc) that no installation in the PC.

Professional MySQL Programming
Available Barnes and Noble
Publisher Wrox Press, Inc.
Authors N/A
Pub Date Late 2001
ISBN 1861005164
Pages 1000
Price $49.99

No description available.

Professional Linux Programming
Available Barnes and Noble
Publisher Wrox Press, Inc.
Authors N/A
Pub Date September 2000
ISBN 1861003013
Pages 1155
Price $47.99

In this follow-up to the best-selling Beginning Linux Programming, you will learn from the authors' real-world knowledge and experience of developing software for Linux; you'll be taken through the development of a sample 'DVD Store' application, with 'theme' chapters addressing different aspects of its implementation. Meanwhile, individual ``take-a-break'' chapters cover important topics that go beyond the bounds of the central theme. All focus on the practical aspects of programming, showing how crucial it is to choose the right tools for the job, use them as they should be used, and get things right first time.

PHP and MySQL Web Development
Available Barnes and Noble
Publisher Sams
Authors Luke Welling, Laura Thomson
Pub Date March 2001
ISBN 0672317842
Pages 700
Price $49.99

PHP and MySQL Web Development introduces you to the advantages of implementing both MySQL and PHP. These advantages are detailed through the provision of both statistics and several case studies. A practical web application is developed throughout the book, providing you with the tools necessary to implement a functional online database. Each function is developed separately, allowing you the choice to incorporate only those parts that you would like to implement. Programming concepts of the PHP language are highlighted, including functions which tie MySQL support into a PHP script and advanced topics regarding table manipulation.

Books recommended by the MySQL Developers

SQL-99 Complete, Really
Available Barnes and Noble
Publisher CMP Books
Authors Peter Gulutzan, Trudy Pelzer
Pub Date April 1999
ISBN 0879305681
Pages 1104
Price $55.96

This book contains complete descriptions of the new standards for syntax, data structures, and retrieval processes of SQL databases. As an example-based reference manual, it includes all of the CLI functions, information, schema tables, and status codes, as well as a working SQL database provided on the companion disk.

C, A reference manual
Available Barnes and Noble
Publisher Prentice Hall
Authors Samuel P. Harbison, Guy L. Steele
Pub Date September 1994
ISBN 0133262243
Pages 480
Price $35.99

A new and improved revision of the bestselling C language reference. This manual introduces the notion of "Clean C", writing C code that can be compiled as a C++ program, C programming style that emphasizes correctness, portability, maintainability, and incorporates the ISO C Amendment 1 (1994) which specifies new facilities for writing portable, international programs in C.

C++ for Real Programmers
Available Barnes and Noble
Publisher Academic Press, Incorporated
Authors Jeff Alger, Jim Keogh
Pub Date February 1998
ISBN 0120499428
Pages 388
Price $39.95

C++ For Real Programmers bridges the gap between C++ as described in beginner and intermediate-level books and C++ as it is practiced by experts. Numerous valuable techniques are described, organized into three simple themes: indirection, class hierarchies, and memory management. It also provides in-depth coverage of template creation, exception handling, pointers and optimization techniques. The focus of the book is on ANSI C++ and, as such, is compiler independent.

C++ For Real Programmers is a revision of Secrets of the C++ Masters and includes a new appendix comparing C++ with Java. The book comes with a 3.5" disk for Windows with source code.

Algorithms in C
Available Barnes and Noble
Publisher Addison Wesley Longman, Inc.
Authors Robert Sedgewick
Pub Date April 1990
ISBN 0201514257
Pages 648
Price $45.75

Algorithms in C describes a variety of algorithms in a number of areas of interest, including: sorting, searching, string-processing, and geometric, graph and mathematical algorithms. The book emphasizes fundamental techniques, providing readers with the tools to confidently implement, run, and debug useful algorithms.

Multithreaded Programming with Pthreads
Available Barnes and Noble
Publisher Prentice Hall
Authors Bil Lewis, Daniel J. Berg
Pub Date October 1997
ISBN 0136807291
Pages 432
Price $34.95

Based on the best-selling Threads Primer, Multithreaded Programming with Pthreads gives you a solid understanding of Posix threads: what they are, how they work, when to use them, and how to optimize them. It retains the clarity and humor of Threads Primer, but includes expanded comparisons to Win32 and OS/2 implementations. Code examples tested on all of the major UNIX platforms are featured along with detailed explanations of how and why they use threads.

Programming the PERL DBI: Database Programming with PERL
Available Barnes and Noble
Publisher O'Reilly & Associates, Incorporated
Authors Alligator Descartes, Tim Bunce
Pub Date February 2000
ISBN 1565926994
Pages 400
Price $27.96

Programming the Perl DBI is coauthored by Alligator Descartes, one of the most active members of the DBI community, and by Tim Bunce, the inventor of DBI. For the uninitiated, the book explains the architecture of DBI and shows you how to write DBI-based programs. For the experienced DBI dabbler, this book explains DBI's nuances and the peculiarities of each individual DBD.

The book includes:


1.2.2 General SQL Information and Tutorials

The following book has been recommended by several people on the MySQL mailing list: 

Judith S. Bowman, Sandra L. Emerson and Marcy Darnovsky
The Practical SQL Handbook: Using Structured Query Language
Second Edition
Addison-Wesley
ISBN 0-201-62623-3
http://www.awl.com

The following book has also received some recommendations by MySQL users: 

Martin Gruber
Understanding SQL
ISBN 0-89588-644-8
Publisher Sybex 510 523 8233
Alameda, CA USA

A SQL tutorial is available on the net at http://w3.one.net/~jhoffman/sqltut.htm

1.2.3 Useful MySQL-related Links

Apart from the following links, you can find and download a lot of MySQL programs, tools and APIs from the Contrib directory.

MySQL

1.2.4 Tutorials and Manuals

MySQL Myths Debunked
MySQL used in the real world.
http://www.4t2.com/mysql
Information about the German MySQL mailing list.
http://www2.rent-a-database.de/mysql/
MySQL handbook in German.
http://www.bitmover.com:8888//home/bk/mysql
Web access to the MySQL BitKeeper repository.
http://www.analysisandsolutions.com/code/mybasic.htm
Beginners MySQL Tutorial on how to install and set up MySQL on a Windows machine.
http://www.devshed.com/Server_Side/MySQL/
A lot of MySQL tutorials.
http://mysql.hitstar.com/
MySQL manual in Chinese.
http://www.linuxplanet.com/linuxplanet/tutorials/1046/1/
Setting Up a MySQL-based Web site.
http://www.hotwired.com/webmonkey/backend/tutorials/tutorial1.html
MySQL-Perl tutorial.
http://www.iserver.com/support/contrib/perl5/modules.html
Installing new Perl modules that require locally installed modules.
http://www.hotwired.com/webmonkey/databases/tutorials/tutorial4.html
PHP/MySQL Tutorial.
http://www.useractive.com/
Hands on tutorial for MySQL.

1.2.5 Porting MySQL/Using MySQL on Different Systems

http://xclave.macnn.com/MySQL/
The Mac OS Xclave. Running MySQL on Mac OS X.
http://www.prnet.de/RegEx/mysql.html
MySQL for Mac OS X Server.
http://www.latencyzero.com/macosx/mysql.html
Building MySQL for Mac OS X.
http://www.essencesw.com/Software/mysqllib.html
New Client libraries for the Mac OS Classic (Macintosh).
http://www.lilback.com/macsql/
Client libraries for Mac OS Classic (Macintosh).
http://sixk.maniasys.com/index_en.html
MySQL for Amiga

1.2.6 Perl-related Links

http://dbimysql.photoflux.com/
Perl DBI with MySQL FAQ.

1.2.7 MySQL Discussion Forums

http://www.weberdev.com/
Examples using MySQL; (check Top 20)
http://futurerealm.com/forum/futureforum.htm
FutureForum Web Discussion Software.

1.2.8 Commercial Applications that Support MySQL

http://www.supportwizard.com/
SupportWizard; Interactive helpdesk on the Web (This product includes a licensed copy of MySQL.)
http://www.sonork.com/
Sonork, Instant Messenger that is not only Internet oriented. It's focused on private networks and on small to medium companies. Client is free, server is free for up to 5 seats.
http://www.stweb.org/
StWeb - Stratos Web and Application server - An easy-to-use, cross platform, Internet/Intranet development and deployment system for development of web-enabled applications. The standard version of StWeb has a native interface to MySQL database.
http://www.rightnowtech.com/
Right Now Web; Web automation for customer service.
http://www.icaap.org/Bazaar/
Bazaar; Interactive Discussion Forums with Web interface.
http://www.phonesweep.com/
PhoneSweepT is the world's first commercial Telephone Scanner. Many break-ins in recent years have come not through the Internet, but through unauthorized dial-up modems. PhoneSweep lets you find these modems by repeatedly placing phone calls to every phone number that your organization controls. PhoneSweep has a built-in expert system that can recognize more than 250 different kinds of remote-access programs, including Carbon Copy(TM), pcANYWHERE(TM), and Windows NT RAS. All information is stored in the SQL database. It then generates a comprehensive report detailing which services were discovered on which dial-up numbers in your organization.

1.2.9 SQL Clients and Report Writers

urSQL
SQL Editor and Query Utility. Custom syntax highlighting, editable results grid, exportable result-sets, basic MySQL admin functions, Etc.. For Windows.
MySQL Data Manager
MySQL Data Manager * is platform independent web client (written in perl) for MySQL server over TCP/IP.
http://ksql.sourceforge.net/
KDE MySQL client.
http://www.ecker-software.de
A Windows GUI client by David Ecker.
http://www.icaap.org/software/kiosk/
Kiosk; a MySQL client for database management. Written in Perl. Will be a part of Bazaar.
http://www.casestudio.com/
Db design tool that supports MySQL 3.23.
http://home.skif.net/~voland/zeos/eng/index.html
Zeos - A client that supports MySQL, Interbase and PostgreSQL.
http://www.geocities.com/SiliconValley/Ridge/4280/GenericReportWriter/grwhome.html
A free report writer in Java
http://www.javaframework.de
MySQLExport - Export of MySQL create statements and data in a lot of different formats (SQL, HTML, CVS, text, ZIP, GZIP...)
http://dlabs.4t2.com
M2D, a MySQL Administration client for Windows. M2D supports administration of MySQL databases, creation of new databases and tables, editing, and more.
http://dlabs.4t2.com
Dexter, a small server written in Perl which can be used as a proxy server for MySQL or as a database extender.
http://www.scibit.com/Products/Software/Utils/Mascon.asp
Mascon is a powerful Win32 GUI for administering MySQL databases.
http://www.rtlabs.com/
MacSQL Monitor. GUI for MySQL, ODBC, and JDBC databases for the Mac OS.

1.2.10 Distributions that Include MySQL

http://www.suse.com/
SuSE Linux (6.1 and above)
http://www.redhat.com/
RedHat Linux (7.0 and above)
http://distro.conectiva.com.br
Conectiva Linux (4.0 and above)

1.2.11 Web Development Tools that Support MySQL

http://www.php.net/
PHP: A server-side HTML-embedded scripting language.
http://www.midgard-project.org
The Midgard Application Server; a powerful Web development environment based on MySQL and PHP.
http://www.smartworker.org
SmartWorker is a platform for Web application development.
http://xsp.lentus.se/
XSP: e(X)tendible (S)erver (P)ages and is a HTML embedded tag language written in Java (previously known as XTAGS.)
http://www.dbServ.de/
dbServ is an extension to a web server to integrate database output into your HTML code. You may use any HTML function in your output. Only the client will stop you. It works as standalone server or as Java servlet.
http://www.chilisoft.com/
Platform independent ASP from Chili!Soft
http://www.voicenet.com/~zellert/tjFM
A JDBC driver for MySQL.
http://www.wernhart.priv.at/php/
MySQL + PHP demos.
http://www.dbwww.com/
ForwardSQL: HTML interface to manipulate MySQL databases.
http://www.daa.com.au/~james/www-sql/
WWW-SQL: Display database information.
http://www.minivend.com/minivend/
Minivend: A Web shopping cart.
http://www.heitml.com/
HeiTML: A server-side extension of HTML and a 4GL language at the same time.
http://www.metahtml.com/
Metahtml: A Dynamic Programming Language for WWW Applications.
http://www.binevolve.com/
VelocityGen for Perl and Tcl.
http://hawkeye.net/
Hawkeye Internet Server Suite.
http://www.fastflow.com/
Network Database Connection For Linux
http://www.wdbi.net/
WDBI: Web browser as a universal front end to databases which supports MySQL well.
http://www.webgroove.com/
WebGroove Script: HTML compiler and server-side scripting language.
http://www.ihtml.com/
A server-side Web site scripting language.
ftp://ftp.igc.apc.org/pub/myodbc/README
How to use MySQL with ColdFusion on Solaris.
http://calistra.com/MySQL/
Calistra's ODBC MySQL Administrator.
http://www.webmerger.com
Webmerger - This CGI tool interprets files and generates dynamic output based on a set of simple tags. Ready-to-run drivers for MySQL and PostgreSQL through ODBC.
http://phpclub.net/
PHPclub - Tips and tricks for PHP.
http://www.penguinservices.com/scripts
MySQL and Perl Scripts.
http://www.widgetchuck.com
The Widgetchuck; Web Site Tools and Gadgets
http://www.adcycle.com/
AdCycle - advertising management software.
http://sourceforge.net/projects/pwpage/
pwPage - provides an extremely fast and simple approach to the creation of database forms. That is, if a database table exists and an HTML page has been constructed using a few simple guidelines, pwPage can be immediately used for table data selections, insertions, updates, deletions and selectable table content reviewing.
http://www.omnis-software.com/products/studio/studio.html
OMNIS Studio is a rapid application development (RAD) tool.
http://www.webplus.com
talentsoft Web+ 4.6 - a powerful and comprehensive development language for use in creating web-based client/server applications without writing complicated, low-level, and time-consuming CGI programs.

1.2.12 Database Design Tools with MySQL Support

http://www.mysql.com/documentation/dezign/
"DeZign for databases" is a database development tool that uses an entity relationship diagram (ERD).

1.2.13 Web Servers with MySQL Tools

ftp://ftp.kcilink.com/pub/
mod_auth_mysql, An Apache authentication module.
http://www.roxen.com/
The Roxen Challenger Web server.

1.2.14 Extensions for Other Programs

http://www.seawood.org/msql_bind/
MySQL support for BIND (The Internet Domain Name Server).
http://www.inet-interactive.com/sendmail/
MySQL support for Sendmail and Procmail.

1.2.15 Using MySQL with Other Programs

http://www.iserver.com/support/addonhelp/database/mysql/msaccess.html
Using MySQL with Access.
http://www.iserver.com/support/contrib/perl5/modules.html
Installing new Perl modules that require locally installed modules.

1.2.16 ODBC-related Links

http://www.iodbc.org/
Popular iODBC Driver Manager (libiodbc) now available as Open Source.
http://users.ids.net/~bjepson/freeODBC/
The FreeODBC Pages.
http://genix.net/unixODBC/
The unixODBC Project goals are to develop and promote unixODBC to be the definitive standard for ODBC on the Linux platform. This is to include GUI support for KDE.
http://www.sw-soft.com/products/BtrieveODBC/
A MySQL-based ODBC driver for Btrieve.

1.2.17 API-related Links

http://www.jppp.com/
Partially implemented TDataset-compatible components for MySQL.
http://www.riverstyx.net/qpopmysql/
qpopmysql - A patch to allow POP3 authentication from a MySQL database. There's also a link to Paul Khavkine's patch for Procmail to allow any MTA to deliver to users in a MySQL database.
http://www.pbc.ottawa.on.ca
Visual Basic class generator for Active X.
http://www.essencesw.com/Software/mysqllib.html
New Client libraries for the Mac OS Classic (Macintosh).
http://www.lilback.com/macsql/
Client libraries for the Macintosh.
http://www.essencesw.com/Plugins/mysqlplug.html
Plugin for REALbasic (for Macintosh)
http://www.iis.ee.ethz.ch/~neeri/macintosh/gusi-qa.html
A library that emulates BSD sockets and pthreads on Macintosh. This can be used if you want to compile the MySQL client library on Mac. It could probably even be sued to port MySQL to Macintosh, but we don't know of anyone that has tried that.
http://www.dedecker.net/jessie/scmdb/
SCMDB - an add-on for SCM that ports the MySQL C library to scheme (SCM). With this library scheme developers can make connections to a MySQL database and use embedded SQL in their programs.

1.2.18 Other MySQL-related Links

SAT
The Small Application Toolkit (SAT) is a collection of utilities intended to simplify the development of small, multi-user, GUI based applications in a (Microsoft -or- X) Windows Client / Unix Server environment.
http://www.wix.com/mysql-hosting/
Registry of Web providers who support MySQL.
http://www.softagency.co.jp/mysql/index.en.html
Links about using MySQL in Japan/Asia.
http://abattoir.cc.ndsu.nodak.edu/~nem/mysql/udf/
MySQL UDF Registry.
http://www.open.com.au/products.html
Commercial Web defect tracking system.
http://www.stonekeep.com/pts/
PTS: Project Tracking System.
http://tomato.nvgc.vt.edu/~hroberts/mot
Job and software tracking system.
http://www.cynergi.net/exportsql/
ExportSQL: A script to export data from Access95+.
http://SAL.KachinaTech.COM/H/1/MYSQL.html
SAL (Scientific Applications on Linux) MySQL entry.
http://www.infotech-nj.com/itech/index.shtml
A consulting company which mentions MySQL in the right company.
http://www.pmpcs.com/
PMP Computer Solutions. Database developers using MySQL and mSQL.
http://www.aewa.org/
Airborne Early Warning Association.
http://www.dedserius.com/y2kmatrix/
Y2K tester.

1.2.19 SQL and Database Interfaces

http://java.sun.com/products/jdbc/
The JDBC database access API.
http://www.gagme.com/mysql
Patch for mSQL Tcl.
http://www.amsoft.ru/easysql/
EasySQL: An ODBC-like driver manager.
http://www.lightlink.com/hessling/rexxsql.html
A REXX interface to SQL databases.
http://www.mytcl.cx/
Tcl interface based on tcl-sql with many bugfixes.
http://www.binevolve.com/~tdarugar/tcl-sql/
Tcl interface.
http://www.contrib.andrew.cmu.edu/~shadow/sql.html
SQL Reference Page with a lot of interesting links.

1.2.20 Examples of MySQL Use

http://www.little6.com/about/linux/
Little6 Inc., An online contract and job finding site that is powered by MySQL, PHP3, and Linux.
http://www.delec.com/is/products/prep/examples/BookShelf/index.html
DELECis - A tool that makes it very easy to create an automatically generated table documentation. They have used MySQL as an example.
http://www.worldrecords.com
World Records - A search engine for information about music that uses MySQL and PHP.
http://www.webtechniques.com/archives/1998/01/note/
A Contact Database using MySQL and PHP.
http://modems.rosenet.net/mysql/
Web based interface and Community Calendar with PHP.
http://www.odbsoft.com/cook/sources.htm
Perl package to generate html from a SQL table structure and for generating SQL statements from an html form.
http://www.gusnet.cx/proj/telsql/
Basic telephone database using DBI/DBD.
http://tecfa.unige.ch/guides/java/staf2x/ex/jdbc/coffee-break
JDBC examples by Daniel K. Schneider.
http://www.spade.com/linux/howto/PostgreSQL-HOWTO-41.html
SQL BNF
http://www.ooc.com/
Object Oriented Concepts Inc; CORBA applications with examples in source.
http://www.pbc.ottawa.on.ca/
DBWiz; Includes an example of how to manage cursors in VB.
http://keilor.cs.umass.edu/pluribus/
Pluribus is a free search engine that learns to improve the quality of its results over time. Pluribus works by recording which pages a user prefers among those returned for a query. A user votes for a page by selecting it; Pluribus then uses that knowledge to improve the quality of the results when someone else submits the same (or similar) query. Uses PHP and MySQL.
http://www.stopbit.com/
Stopbit - A technology news site using MySQL and PHP.
http://www.linuxsupportline.com/~kalendar/
KDE based calendar manager - The calendar manager has both single user (file based) and multi-user (MySQL database) support.
http://tim.desert.net/~tim/imger/
Example of storing/retrieving images with MySQL and CGI.
http://www.penguinservices.com/scripts
Online shopping cart system.
http://www.city-gallery.com/album/
Old Photo Album - The album is a collaborative popular history of photography project that generates all pages from data stored in a MySQL database. Pages are dynamically generated through a php3 interface to the database content. Users contribute images and descriptions. Contributed images are stored on the web server to avoid storing them in the database as BLOBs. All other information is stored on the shared MySQL server.

1.2.21 General Database Links

http://www.pcslink.com/~ej/dbweb.html
Database Jump Site
http://black.hole-in-the.net/guy/webdb/
Homepage of the webdb-l (Web Databases) mailing list.
http://www.symbolstone.org/technology/perl/DBI/index.html
Perl DBI/DBD modules homepage.
http://www.student.uni-koeln.de/cygwin/
Cygwin tools. Unix on top of Windows.
http://dbasecentral.com/
dbasecentral.com; Development and distribution of powerful and easy-to-use database applications and systems.
http://www.tek-tips.com/
Tek-Tips Forums are 800+ independent peer-to-peer non-commercial support forums for Computer Professionals. Features include automatic e-mail notification of responses, a links library, and member confidentiality guaranteed.
http://www.public.asu.edu/~peterjn/btree/
B-Trees: Balanced Tree Data Structures.
http://www.fit.qut.edu.au/~maire/baobab/lecture/sld001.htm
A lecture about B-Trees.

There are also many Web pages that use MySQL. See section C Some MySQL Users. Send any additions to this list to webmaster@mysql.com. We now require that you show a MySQL logo somewhere if you wish your site to be added. It is okay to have it on a ``used tools'' page or something similar.

1.2.22 MySQL Mailing Lists

This section introduces you to the MySQL mailing lists, and gives some guidelines as to how to use them.

1.2.22.1 The MySQL Mailing Lists

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. 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 Website.

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 that 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
This is for announcement of new versions of MySQL and related programs. This is a low volume list all MySQL users should subscribe to.
mysql-subscribe@lists.mysql.com mysql
The main list for general MySQL discussion. Please note that some topics are better discussed on the more-specialized lists. If you post to the wrong list, you may not get an answer!
mysql-digest-subscribe@lists.mysql.com mysql-digest
The 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
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 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 there are only small code changes involved, we will also post a patch that fixes the problem.
bugs-digest-subscribe@lists.mysql.com bugs-digest
The bugs list in digest form.
internals-subscribe@lists.mysql.com internals
A list for people who work on the MySQL code. On this list one can also discuss MySQL development and post patches.
internals-digest-subscribe@lists.mysql.com internals-digest
A digest version of the internals list.
java-subscribe@lists.mysql.com java
Discussion about MySQL and Java. Mostly about the JDBC drivers.
java-digest-subscribe@lists.mysql.com java-digest
A digest version of the java list.
win32-subscribe@lists.mysql.com win32
All things concerning MySQL on Microsoft operating systems such as Win95, Win98, NT, and Win2000.
win32-digest-subscribe@lists.mysql.com win32-digest
A digest version of the win32 list.
myodbc-subscribe@lists.mysql.com myodbc
All things about connecting to MySQL with ODBC.
myodbc-digest-subscribe@lists.mysql.com myodbc-digest
A digest version of the myodbc list.
plusplus-subscribe@lists.mysql.com plusplus
All things concerning programming with the C++ API to MySQL.
plusplus-digest-subscribe@lists.mysql.com plusplus-digest
A digest version of the plusplus list.
msql-mysql-modules-subscribe@lists.mysql.com msql-mysql-modules
A list about the Perl support in MySQL. msql-mysql-modules
msql-mysql-modules-digest-subscribe@lists.mysql.com msql-mysql-modules-digest
A digest version of the msql-mysql-modules list.

You subscribe or unsubscribe to all lists in the same way as described above. 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 1.3.5 Types of Commercial Support.

The following table shows some MySQL mailing in other languages 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
Email subscribe mysql your@email.address to this list.
mysql-de-request@lists.4t2.com A German mailing list
Email subscribe mysql-de your@email.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
Email subscribe mysql-br your@email.address to this list.
mysql-alta@elistas.net A Spanish mailing list
Email subscribe mysql your@email.address to this list.

1.2.22.2 Asking Questions or Reporting Bugs

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.

1.2.22.3 How to Report Bugs or Problems

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 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 there are only small code changes involved to correct this problem, we will also post a patch that fixes the problem.

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 MySQL 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 or not 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 H.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 below).

Please include the following information in your report:

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 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 summarize 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!

1.2.22.4 Guidelines for Answering Question on the Mailing List

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 summarize 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!

1.3 MySQL Licensing and Support

This section describes MySQL support and licensing arrangements:

1.3.1 MySQL Licensing Policy

The formal terms of the GPL license can be found at section K GNU GENERAL PUBLIC LICENSE. Basically, our licensing policy and interpretation of the GPL is as follows:

Note that older versions of MySQL are still using a more strict license. See the documentation for that version for more information. If you need a commercial MySQL license, because the GPL license doesn't suit your application, you can buy one at https://order.mysql.com/.

For normal internal use, MySQL costs nothing. You do not have to pay us if you do not want to.

A license is required if:

A license is NOT required if:

For circumstances under which a MySQL license is required, you need a license per machine that runs the mysqld server. However, a multiple-CPU machine counts as a single machine, and there is no restriction on the number of MySQL servers that run on one machine, or on the number of clients concurrently connected to a server running on that machine!

If you have any questions as to whether or not a license is required for your particular use of MySQL, please read this again and then contact us. See section 1.3.4.2 Contact Information.

If you require a MySQL license, the easiest way to pay for it is to use the license form on MySQL's secure server at https://order.mysql.com/. Other forms of payment are discussed in section 1.3.4.1 Payment information.

1.3.2 Copyrights Used by MySQL

There are several different copyrights on the MySQL distribution:

  1. The MySQL-specific source needed to build the mysqlclient library is licensed under the LGPL and programs in the `client' directory is GPL. Each file has a header that shows which copyright is used for that file.
  2. The client library and the (GNU getopt) library are covered by the ``GNU LIBRARY GENERAL PUBLIC LICENSE.'' See section L GNU LESSER GENERAL PUBLIC LICENSE.
  3. Some parts of the source (the regexp library) are covered by a Berkeley-style copyright.
  4. All the source in the server and the (GNU readline) library is covered by the ``GNU GENERAL PUBLIC LICENSE.'' See section K GNU GENERAL PUBLIC LICENSE. This is also available as the file `COPYING' in the distributions.

One goal is that the SQL client library should be free enough that it is possible to add MySQL support into commercial products without a license. For this reason, we chose the LGPL license for the client code.

This means that you can use MySQL for free with any program that uses any of the free software licenses. MySQL is also free for any end user for his own or company usage.

However, if you use MySQL for something important to you, you may want to help secure its development by purchasing licenses or a support contract. See section 1.3.5 Types of Commercial Support.

1.3.2.1 Copyright Changes

Version 3.22 of MySQL is still using a more strict license. See the documentation for that version for more information.

1.3.3 Example Licensing Situations

This section describes some situations illustrating whether or not you must license the MySQL server. Generally these examples involve providing MySQL as an integral part of a product.

Note that a single MySQL license covers any number of CPUs and mysqld servers on a machine! There is no artificial limit on the number of clients that connect to the server in any way.

1.3.3.1 Selling Products that use MySQL

To determine whether or not you need a MySQL license when selling your application, you should ask whether the proper functioning of your application is dependent on the use of MySQL and whether you include the MySQL server with your product. There are several cases to consider:

1.3.3.2 ISP MySQL Services

Internet Service Providers (ISPs) often host MySQL servers for their customers. With the GPL license this does not require a license.

On the other hand, 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 their MySQL installation, their ISP will be able to solve the problem for them (in some cases with the help from the MySQL development team).

All ISPs that want to keep themselves up-to-date should subscribe to our announce mailing list so that they can be aware of fatal issues that may be relevant for their MySQL installations.

Note that if the ISP doesn't have a license for MySQL, it should give its customers at least read access to the source of the MySQL installation so that its customer can verify that it is patched correctly.

1.3.3.3 Running a Web Server Using MySQL

If you use MySQL in conjunction with a Web server on Unix, you don't have to pay for a license.

This is true even if you run a commercial Web server that uses MySQL, because you are not selling an embedded MySQL version yourself. However, in this case we would like you to purchase MySQL support, because MySQL is helping your enterprise.

1.3.4 MySQL Licensing and Support Costs

Our current license prices are shown below. To make a purchase, please visit https://order.mysql.com/.

If you pay by credit card, the currency is EURO (European Union Euro) so the prices will differ slightly.

Number of licenses Per copy
1-9 230 EURO
10-24 138 EURO
25-49 117 EURO
50-99 102 EURO
100-249 91 EURO
250-499 76 EURO
500-999 66 EURO

For high volume (OEM) purchases, please contact sales@mysql.com.

For OEM purchases, you must act as the middle-man for eventual problems or extension requests from your users. We also require that OEM customers have at least an extended e-mail support contract. Note that OEM licenses only apply for products where the user doesn't have direct access to the MySQL server (embedded system). In other words, the MySQL server should only be used with the application that was supplied you.

If you have a low-margin, high-volume product, you can always talk to us about other terms (for example, a percent of the sale price). If you do, please be informative about your product, pricing, market, and any other information that may be relevant.

A full-price license is not a support agreement and includes very minimal support. This means that we try to answer any relevant questions. If the answer is in the documentation, we will direct you to the appropriate section. If you have not purchased a license or support, we probably will not answer at all.

If you discover what we consider a real bug, we are likely to fix it in any case. But if you pay for support we will notify you about the fix status instead of just fixing it in a later release.

More comprehensive support is sold separately. Descriptions of what each level of support includes are given in section 1.3.5 Types of Commercial Support. Costs for the various types of commercial support are shown below. Support level prices are in EURO (European Union Euro). One EURO is about 1.06 USD.

Type of support Cost per year
Basic e-mail support. See section 1.3.5.1 Basic E-mail Support. EURO 200
Extended e-mail support See section 1.3.5.2 Extended E-mail Support. EURO 1000
Login support See section 1.3.5.3 Login Support. EURO 2000
Extended login support See section 1.3.5.4 Extended Login Support. EURO 5000
Telephone support See section 1.3.5.5 Telephone Support. EURO 12000

You may upgrade from any lower level of support to a higher level of support for the difference in price between the two support levels.

We do also provide telephone support (mostly emergency support but also 24/7 support). This support option doesn't however have a fixed price but is negotiated for case to case. If you are interested in this option you can email sales@mysql.com and tell us about your needs.

Note that as our sales staff is very busy, it may take some time until your request is handled. Our support staff does however always answer promptly to support questions!

1.3.4.1 Payment information

Currently we can take SWIFT payments, checks, or credit cards.

Payment should be made to: 

Postgirot Bank AB
105 06 STOCKHOLM, SWEDEN

MySQL AB
BOX 6434
11382 STOCKHOLM, SWEDEN

SWIFT address: PGSI SESS
Account number: 96 77 06 - 3

Specify: license and/or support and your name and e-mail address.

In Europe and Japan you can use EuroGiro (that should be less expensive) to the same account.

If you want to pay by check, make it payable to ``MySQL Finland AB'' and mail it to the address below: 

MySQL AB
BOX 6434, Torsgatan 21
11382 STOCKHOLM, SWEDEN

If you want to pay by credit card over the Internet, you can use MySQL AB's secure license form.

You can also print a copy of the license form, fill it in, and send it by fax to:

+46-8-729 69 05

If you want us to bill you, you can use the license form and write ``bill us'' in the comment field. You can also mail a message to sales@mysql.com (not mysql@lists.mysql.com!) with your company information and ask us to bill you.

1.3.4.2 Contact Information

For commercial licensing, please contact the MySQL licensing team. The much preferred method is by e-mail to licensing@mysql.com. Fax is also possible but handling of these may take much longer (Fax +46-8-729 69 05).

If you represent a business that is interested in partnering with MySQL, please send e-mail to partner@mysql.com.

For timely, precise answers to technical questions about MySQL you should order one of our support contracts. MySQL support is provided by the MySQL developers so the standard is extremely high.

If you are interested in placing a banner advertisement on our Web site, please send e-mail to advertising@mysql.com.

If you are interested in any of the jobs listed in our jobs section, please send e-mail to jobs@mysql.com.

For general discussion amongst our many users, please direct your attention to the appropriate mailing list.

For general information inquires, please send e-mail to info@mysql.com.

For questions or comments about the workings or content of the Web site, please send e-mail to webmaster@mysql.com.

1.3.5 Types of Commercial Support

The following is true of all support options:

1.3.5.1 Basic E-mail Support

Basic e-mail support is a very inexpensive support option and should be thought of more as a way to support our development of MySQL than as a real support option. We at MySQL do give a lot of free support in all the different MySQL lists, and the money we get from basic e-mail support is largely used to make this possible.

At this support level, the MySQL mailing lists are the preferred means of communication. Questions normally should be mailed to the primary mailing list (mysql@lists.mysql.com) or one of the other regular lists (for example, win32@lists.mysql.com for Windows-related MySQL questions), as someone else already may have experienced and solved the problem you have. See section 1.2.22.2 Asking Questions or Reporting Bugs.

However, by purchasing basic e-mail support, you also have access to the support address mysql-support@mysql.com, which is not available as part of the minimal support that you get by purchasing a MySQL license. This means that for especially critical questions, you can cross-post your message to mysql-support@mysql.com. (If the message contains sensitive data, you should post only to mysql-support@mysql.com.)

REMEMBER! to ALWAYS include your registration number and expiration date when you send a message to mysql-support@mysql.com.

Note that if you have encountered a critical, repeatable bug, and follow the rules outlined in the manual section of how to report bugs and send it to bugs@lists.mysql.com, we promise to try to fix this as soon as possible, regardless of your support level! See section 1.2.22.3 How to Report Bugs or Problems.

Basic e-mail support includes the following types of service:

1.3.5.2 Extended E-mail Support

Extended e-mail support includes everything in basic e-mail support with these additions:

1.3.5.3 Login Support

Login support includes everything in extended e-mail support with these additions:

1.3.5.4 Extended Login Support

Extended login support includes everything in login support with these additions:

1.3.5.5 Telephone Support

Telephone support includes everything in extended login support with these additions:

1.3.5.6 Support for other table handlers

To get support for BDB tables, InnoDB tables you have to pay an additional 30% on the standard support price for each of the table handlers you would like to have support for.

We at MySQL AB will help you create a proper bug report for the table handler and submit it to the developers for the specific table handler. We will also do our best to ensure that you will get a timely answer or solution from the developers of the table handler.

Even if we are quite confident that we can solve most problems within a timely manner, we can't guarantee a quick solution for any problems you can get with the different table handlers. We will however do our best to help you get the problem solved.

1.4 How Standards-compatible Is MySQL?

This section describes how MySQL relates to the ANSI SQL standards. MySQL 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, and how to work around some differences.

1.4.1 MySQL Extensions to ANSI SQL92

MySQL 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 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 only be executed if the MySQL version is equal to or newer than the used version number: 

CREATE /*!32302 TEMPORARY */ TABLE (a int);

The above means that if you have Version 3.23.02 or newer, then MySQL will use the TEMPORARY keyword.

MySQL extensions are listed below:

1.4.2 MySQL Differences Compared to ANSI SQL92

We try to make MySQL follow the ANSI SQL standard and the ODBC SQL standard, but in some cases MySQL does some things differently:

1.4.3 Running MySQL in ANSI Mode

If you start mysqld with the --ansi option, the following behavior of MySQL changes:

This is the same as using --sql-mode=REAL_AS_FLOAT,PIPES_AS_CONCAT,ANSI_QUOTES,IGNORE_SPACE,SERIALIZE,ONLY_FULL_GROUP_BY.

1.4.4 Functionality Missing from MySQL

The following functionality is missing in the current version of MySQL. For a prioritized list indicating when new extensions may be added to MySQL, you should consult the online MySQL TODO list. That is the latest version of the TODO list in this manual. See section 1.6 MySQL and the future (The TODO).

1.4.4.1 Sub-selects

The following will not yet work in MySQL: 

SELECT * FROM table1 WHERE id IN (SELECT id FROM table2);
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);

However, in many cases you can rewrite the query without a sub-select: 

SELECT table1.* FROM table1,table2 WHERE table1.id=table2.id;
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 sub-selects). For this situation there are two options available until subqueries are supported by MySQL.

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 contruct 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: 

prompt> mysql --skip-column-names mydb < myscript.sql | mysql mydb

MySQL only supports INSERT ... SELECT ... and REPLACE ... SELECT ... Independent sub-selects will probably be available in Version 4.0. You can now use the function IN() in other contexts, however.

1.4.4.2 SELECT INTO TABLE

MySQL doesn't yet support the Oracle SQL extension: SELECT ... INTO TABLE .... MySQL supports instead the ANSI SQL syntax INSERT INTO ... SELECT ..., which is basically the same thing. See section 6.4.2.1 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 to solve your problem.

1.4.4.3 Transactions

As MySQL does nowadays support transactions, the following discussion is only valid if you are only using the non-transaction-safe table types. See section 6.7.1 BEGIN/COMMIT/ROLLBACK Syntax.

The question is often asked, by the curious and the critical, ``Why is MySQL not a transactional database?'' or ``Why does MySQL not support transactions?''

MySQL has made a conscious decision to support another paradigm for data integrity, ``atomic operations.'' It is our thinking and experience that atomic operations offer equal or even better integrity with much better performance. We, nonetheless, appreciate and understand the transactional database paradigm and plan, within the next few releases, to introduce transaction-safe tables on a per table basis. We will be giving our users the possibility to decide if they need the speed of atomic operations or if they need to use transactional features in their applications.

How does one use the features of MySQL to maintain rigorous integrity and how do these features compare with the transactional paradigm?

First, in the transactional paradigm, if your applications are written in a way that is dependent on the calling of ``rollback'' instead of ``commit'' in critical situations, then transactions are more convenient. Moreover, transactions 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, in almost all cases, allows you to solve for 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 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.

Moreover, fatal transactional updates can be rewritten to be atomic. In fact,we will go so far as to say that all integrity problems that transactions solve can be done with 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.

Not even transactions can prevent all loss if the server goes down. In such cases even a transactional system can lose data. The difference between different systems lies in just how small the time-lap is where they could lose data. No system is 100% secure, only ``secure enough.'' Even Oracle, reputed to be the safest of transactional databases, is reported to sometimes lose data in such situations.

To be safe with MySQL, you only need to have backups and have the update logging turned on. With this you can recover from any situation that you could with any transactional database. It is, of course, always good to have backups, independent of which database you use.

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, and they may have to do a little more work with MySQL to either think differently or write more. If you are new to the atomic operations paradigm, or more familiar or more comfortable with transactions, do not jump to the conclusion that MySQL has not addressed these issues. Reliability and integrity are foremost in our minds. Recent estimates indicate that there are more than 1,000,000 mysqld servers currently running, many of which are in production environments. We hear very, very seldom from our users that they have lost any data, and in almost all of those cases user error is involved. This is, in our opinion, the best proof of MySQL's stability and reliability.

Lastly, in situations where integrity is of highest importance, MySQL's current features allow for transaction-level or better reliability and integrity. 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), then 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 6.4.3 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 on transaction based systems if you are not very careful). MySQL also guarantees that there will not be any dirty reads. You can find some example of how to write atomic updates in the commit-rollback section. See section 1.4.6 How to Cope Without COMMIT/ROLLBACK.

We have thought quite a bit about integrity and performance, and we believe that our atomic operations paradigm allows for both high reliability and extremely high performance, on the order of three to five times the speed of the fastest and most optimally tuned of transactional databases. We didn't leave out transactions because they are hard to do. The main reason we went with atomic operations as opposed to transactions is that by doing this we could apply many speed optimizations that would not otherwise have been possible.

Many of our users who have speed foremost in their minds are not at all concerned about transactions. For them transactions are not an issue. For those of our users who are concerned with or have wondered about transactions vis-a-vis MySQL, there is a ``MySQL way'' as we have outlined above. For those where safety is more important than speed, we recommend them to use the BDB, or InnoDB tables for all their critical data. See section 7 MySQL Table Types.

One final note: We are currently working on a safe replication schema that we believe to be better than any commercial replication system we know of. This system will work most reliably under the atomic operations, non-transactional, paradigm. Stay tuned.

1.4.4.4 Stored Procedures and Triggers

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 reissuing 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, but without triggers. Triggers usually slow down everything, even queries for which they are not needed.

To see when MySQL might get stored procedures, see section 1.6 MySQL and the future (The TODO).

1.4.4.5 Foreign Keys

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.

The FOREIGN KEY syntax in MySQL exists only for compatibility with other SQL vendors' CREATE TABLE commands; it doesn't do anything. 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. MySQL only supports these clauses because some applications require them to exist (regardless of whether or not they work).

In MySQL, 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 the near future we will extend the FOREIGN KEY implementation so that at least 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 application that can't easily be coded to avoid them.

1.4.4.6 Reasons NOT to Use Foreign Keys constraints

There are so many problems with foreign key constraints that we don't know where to start:

The only nice aspect of FOREIGN KEY is that it gives ODBC and some other client programs the ability to see how a table is connected and to use this to show connection diagrams and to help in building applications.

MySQL will soon store FOREIGN KEY definitions so that a client can ask for and receive an answer about how the original connection was made. The current `.frm' file format does not have any place for it. At a later stage we will implement the foreign key constraints for application that can't easily be coded to avoid them.

1.4.4.7 Views

MySQL doesn't yet support views, but we plan to implement these to about 4.1.

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 is mostly used in applications and on web system 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 to restrict access to columns as MySQL has a very sophisticated privilege system. See section 4.2 General Security Issues and the MySQL Access Privilege System.

1.4.4.8 `--' as the Start of a Comment

Some other SQL databases use `--' to start comments. MySQL has `#' as the start comment character, even if the mysql command-line tool removes all lines that start with `--'. You can also use the C comment style /* this is a comment */ with MySQL. See section 6.1.5 Comment Syntax.

MySQL Version 3.23.3 and above supports the `--' comment style only if the comment is followed by a space. This is because this degenerate 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!

What do you think will happen when the value of payment is negative?

Because 1--1 is legal in SQL, we think it is terrible that `--' means start comment.

In MySQL Version 3.23 you can, however, use: 1-- This is a comment

The following discussion only concerns you if you are running a MySQL version earlier than Version 3.23:

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

1.4.5 What Standards Does MySQL Follow?

Entry level SQL92. ODBC levels 0-2.

1.4.6 How to Cope Without COMMIT/ROLLBACK

The following mostly applies only for ISAM, MyISAM, and HEAP tables. If you only use transaction-safe tables (BDB, or InnoDB tables) in an an update, you can do COMMIT and ROLLBACK also with MySQL. See section 6.7.1 BEGIN/COMMIT/ROLLBACK Syntax.

The problem with handling COMMIT-ROLLBACK efficiently with the above table types would require a completely different table layout than MySQL uses today. The table type would also need extra threads that do automatic cleanups on the tables, and the disk usage would be much higher. This would make these table types about 2-4 times slower than they are today.

For the moment, we prefer implementing the SQL server language (something like stored procedures). With this you would very seldom really need COMMIT-ROLLBACK. This would also give much better performance.

Loops that need transactions normally can be coded with the help of LOCK TABLES, and you don't need cursors when you can update records on the fly.

We at TcX had a greater need for a real fast database than a 100% general database. Whenever we find a way to implement these features without any speed loss, we will probably do it. For the moment, there are many more important things to do. Check the TODO for how we prioritize things at the moment. (Customers with higher levels of support can alter this, so things may be reprioritized.)

The current problem is actually ROLLBACK. Without ROLLBACK, you can do any kind of COMMIT action with LOCK TABLES. To support ROLLBACK with the above table types, MySQL would have to be changed to store all old records that were updated and revert everything back to the starting point if ROLLBACK was issued. For simple cases, this isn't that hard to do (the current isamlog could be used for this purpose), but it would be much more difficult to implement ROLLBACK for ALTER/DROP/CREATE TABLE.

To avoid using ROLLBACK, you can use the following strategy:

  1. Use LOCK TABLES ... to lock all the tables you want to access.
  2. Test conditions.
  3. Update if everything is okay.
  4. Use UNLOCK TABLES to release your locks.

This is usually a much faster method than using transactions with possible 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.

You can also use functions to update records in a single operation. You can get a very efficient application by using the following techniques:

For example, when we are doing updates to some customer information, we update only the customer data that has changed and test only that none of the changed data, or data that depend on the changed data, has changed compared to the original row. The test for changed data is done with the 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 have 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.

In many cases, users have wanted 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 8.4.3.126 mysql_insert_id().

At MySQL AB, we have never had any need for row-level locking because we have always been able to code around it. Some cases really need row locking, but they are very few. If you want row-level locking, you can use a flag column in the table and do something like this: 

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 MySQL changed the above query to: 

UPDATE tbl_name SET row_flag=1 WHERE id=ID and row_flag <> 1;

1.4.7 Known errors and design deficiencies in MySQL

The following problems are known and have a very high priority to get fixed:

The following problems are known and will be fixed in due time:

The following are known bugs in earlier versions of MySQL:

For platform-specific bugs, see the sections about compiling and porting.

1.5 How MySQL Compares to Other Databases

This section compares MySQL to other popular databases.

This section has been written by the MySQL developers, so it should be read with that in mind. There are no factual errors contained in this section that we know of. If you find something which you believe to be an error, please contact us about it at docs@mysql.com.

For a list of all supported limits, functions, and types, see the crash-me Web page at http://www.mysql.com/information/crash-me.php.

1.5.1 How MySQL Compares to mSQL

Performance
For a true comparison of speed, consult the growing MySQL benchmark suite. See section 5.1.4 The MySQL Benchmark Suite. Because there is no thread creation overhead, a small parser, few features, and simple security, mSQL should be quicker at: Because these operations are so simple, it is hard to be better at them when you have a higher startup overhead. After the connection is established, MySQL should perform much better. On the other hand, MySQL is much faster than mSQL (and most other SQL implementations) on the following:
SQL Features
Disk Space Efficiency
That is, how small can you make your tables? MySQL has very precise types, so you can create tables that take very little space. An example of a useful MySQL datatype is the MEDIUMINT that is 3 bytes long. If you have 100,000,000 records, saving even one byte per record is very important. mSQL2 has a more limited set of column types, so it is more difficult to get small tables.
Stability
This is harder to judge objectively. For a discussion of MySQL stability, see section 1.1.7 How Stable Is MySQL?. We have no experience with mSQL stability, so we cannot say anything about that.
Price
Another important issue is the license. MySQL has a more flexible license than 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. (You are required to get a license if you include MySQL with a product that you sell, of course.)
Perl Interfaces
MySQL has basically the same interfaces to Perl as mSQL with some added features.
JDBC (Java)
MySQL currently has a lot of different JDBC drivers: The recommended driver is the mm driver. The Resin driver may also be good (at least the benchmarks looks good), but we haven't received that much information about this yet. We know that mSQL has a JDBC driver, but we have too little experience with it to compare.
Rate of Development
MySQL has a very small team of developers, but we are quite used to coding C and C++ very rapidly. Because threads, functions, 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 G MySQL change history). It should be pretty obvious which one has developed most rapidly.
Utility Programs
Both mSQL and MySQL have many interesting third-party tools. Because it is very easy to port upward (from mSQL to MySQL), almost all the interesting applications that are available for mSQL are also available for MySQL. MySQL comes with a simple msql2mysql program that fixes differences in spelling between mSQL and MySQL 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 usually takes a couple of minutes.

1.5.1.1 How to Convert mSQL Tools for MySQL

According to our experience, it would just take a few hours 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:

  1. Run the shell script msql2mysql on the source. This requires the replace program, which is distributed with MySQL.
  2. Compile.
  3. Fix all compiler errors.

Differences between the mSQL C API and the MySQL C API are:

1.5.1.2 How mSQL and MySQL Client/Server Communications Protocols Differ

There 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 below:

1.5.1.3 How mSQL 2.0 SQL Syntax Differs from MySQL

Column types

MySQL
Has the following additional types (among others; see section 6.5.3 CREATE TABLE Syntax):
MySQL also supports the following additional type attributes:
mSQL2
mSQL column types correspond to the MySQL types shown below:
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
Indexes may be specified at table creation time with the CREATE TABLE statement.
mSQL
Indexes must be created after the table has been created, with separate CREATE INDEX statements.

To Insert a Unique Identifier into a Table

MySQL
Use AUTO_INCREMENT as a column type specifier. See section 8.4.3.126 mysql_insert_id().
mSQL
Create a SEQUENCE on a table and select the _seq column.

To Obtain a Unique Identifier for a Row

MySQL
Add a 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
Use the _rowid column. Observe that _rowid may change over time depending on many factors.

To Get the Time a Column Was Last Modified

MySQL
Add a 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
Use the _timestamp column.

NULL Value Comparisons

MySQL
MySQL follows ANSI SQL, and a comparison with NULL is always NULL.
mSQL
In 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.

String Comparisons

MySQL
Normally, string comparisons are performed in case-independent fashion with the sort order determined by the current character set (ISO-8859-1 Latin1 by default). If you don't like this, declare your columns with the BINARY attribute, which causes comparisons to be done according to the ASCII order used on the MySQL server host.
mSQL
All string comparisons are performed in case-sensitive fashion with sorting in ASCII order.

Case-insensitive Searching

MySQL
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 wild-card character.
mSQL
Use CLIKE.

Handling of Trailing Spaces

MySQL
Strips all spaces at the end of CHAR and VARCHAR columns. Use a TEXT column if this behavior is not desired.
mSQL
Retains trailing space.

WHERE Clauses

MySQL
MySQL correctly prioritizes everything (AND is evaluated before OR). To get mSQL behavior in MySQL, use parentheses (as shown in an example below).
mSQL
Evaluates everything from left to right. This means that some logical calculations with more than three arguments cannot be expressed in any way. It also means you must change some queries when you upgrade to MySQL. You do this easily by adding parentheses. Suppose you have the following mSQL query: 
mysql> SELECT * FROM table WHERE a=1 AND b=2 OR a=3 AND b=4;
To make MySQL 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
Has tables to store grant (permission) options per user, host, and database. See section 4.2.5 How the Privilege System Works.
mSQL
Has a file `mSQL.acl' in which you can grant read/write privileges for users.

1.5.2 How MySQL Compares to PostgreSQL

When 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 database as good as possible, so we are both a serious choice 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 because we don't have a full knowledge of all PostgreSQL features while we know MySQL througly, 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 are both widely used products, but with different design goals, even if we are both striving to be ANSI SQL compatible. This means that for some applications MySQL is more suitable and for others PostgreSQL is more suitable. When choosing which database to use, you should first check if the database's feature set satisfies your application. If you need speed, MySQL is probably your best choice. If you need some of the extra features that only PostgreSQL can offer, you should use PostgreSQL.

1.5.2.1 MySQL and PostgreSQL development strategies

When adding things to MySQL 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 3 weeks, which a major branch every year. All releases are throughly 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 prioritize adding a lot of new features, instead of implementing them optimally, because one can always optimize things later if there arises a need for this.

Another big difference between MySQL and PostgreSQL is that nearly all of the code in the MySQL server are 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 where the majority of the code is coded by a big group of people with different backgrounds. It was only recently that the PostgreSQL developers announced that they current developer group had finally had time to take a look at all the code in the current PostgreSQL release.

Both of the above development methods has it's own merits and drawbacks. We here at MySQL AB think of course that our model is better because our model gives better code consistence, 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.

1.5.2.2 Featurewise Comparison of MySQL and PostgreSQL

On the crash-me page 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 respective database. The above web page is however extremely useful when you want to ensure that your applications works with many different databases or when you want to convert your application from one datbase to another.

MySQL offers the following advantages over PostgreSQL:

Drawbacks with MySQL compared to PostgreSQL:

PostgreSQL offers currently the following advantages over MySQL:

Note that because we know the MySQL road map, we have included in the following table the version when MySQL should support this feature. Unfortunately we couldn't do this for previous comparison, because we don't know the PostgreSQL roadmap.

Feature MySQL version
Subselects 4.1
Foreign keys 4.0 and 4.1
Views. 4.2
Stored procedures in multiple languages 4.1
Extensible type system. Not planed
Unions 4.0.
Full join. 4.0 or 4.1.
Triggers. 4.1
Constrainst 4.1
Cursors 4.1 or 4.2
Extensible index types like R-trees R-trees are planned to 4.2
Inherited tables Not planned

Other reasons to use PostgreSQL:

Drawbacks with PostgreSQL compared to MySQL:

For a complete list of drawbacks, you should also examine the first table in this section.

1.5.2.3 Benchmarking MySQL and PostgreSQL

The only open source benchmark, that we know of, that can be used to benchmark MySQL 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 the definitive benchmark for databases, but unfortunately we haven't got 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() between 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 deamon) died and the database was so corrupted that it was impossible to restart postmaster. (The details about the machine we run the benchmark can be found on the benchmark page). After this happened twice, we decided to postpone the --fast test until next PostgreSQL release.

Before going to the other benchmarks we know of, We would like to give some background to benchmarks:

It's very easy to write a test that shows ANY database to be best database in the world, by just restricting the test to something the database is very good at and not test anything that the database is not good at; If one after this publish the result with a single figure things is even easier.

This would be like we would measure the speed of MySQL compared to PostgreSQL by looking at the summary time of the MySQL benchmarks on our web page. Based on this MySQL 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 is more than 2000 times faster than PostgreSQL.

The case is that MySQL does a lot of optimizations that PostgreSQL doesn't do and the other way around. An SQL optimizer is a very complex thing and a company could spend years on just making the optimizer 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 shows 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 claims that PostgreSQL performers better than MySQL. 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 against all databases.

One is the benchmark paid for by Great Bridge.

This is the worst benchmark we have ever seen anyone ever conduct. This was not only tuned to only test what PostgreSQL is absolutely best at, it was also totally unfair against every other database involved in the test.

NOTE: We know that not even some of the main PostgreSQL developers did like the way Great Bridge conducted the benchmark, so we don't blame them for the way the benchmark was made.

This benchmark has been condemned in a lot of postings and newsgroups so we will here just shortly repeat some things that where wrong with it.

Tim Perdue, a long time PostgreSQL fan and a reluctant MySQL user published a comparison on phpbuider.

When we got aware of the comparison, we phoned Tim Perdue about this because there was a lot of strange things in his results. For example, he claimed that MySQL 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 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 (Linux kernels before 2.4 had a problem with this but we have documented 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 with. In any of the above 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 :(

Conclusion:

The only benchmarks that exist today that anyone can download and run against MySQLand PostgreSQL is the MySQL benchmarks. We here at MySQL 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 a 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 shows otherwise. With this we don't want to say that PostgreSQL isn't good at many things (It is!) We would just like to see a fair test where they are very good so that we could get some friendly competition going!

For more information about our benchmarks suite see See section 5.1.4 The MySQL Benchmark Suite.

We are working on an even better benchmark suite, including much better documentation of what the individual tests really do and how to add more tests to the suite.

1.6 MySQL and the future (The TODO)

This appendix lists the features that we plan to implement in MySQL.

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 1.3 MySQL Licensing and Support.

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 sacrifying the speed or compromise the code.

1.6.1 Things that should be in 4.0

We plan to make MySQL Version 4.0 a ``quick'' release where we only add some new stuff to enable others to help us with developing new features into Version 4.1. The MySQL 4.0 version should only take us about a month to make after which we want to stabilize it and start working on Version 4.1. Version 4.0 should have the following new features:

The news section for 4.0 includes a list of the features we have already implemented in the 4.0 tree. See section G.1 Changes in release 4.0.x (Development; Alpha).

1.6.2 Things that must be done in the real near future

1.6.3 Things that have to be done sometime

Time is given according to amount of work, not real time.

1.6.4 Some things we don't have any plans to do

2 MySQL Installation

This chapter describes how to obtain and install MySQL:

2.1 Quick Standard Installation of MySQL

2.1.1 Installing MySQL on Linux

The recommended way to install MySQL on Linux is by using an RPM file. The MySQL RPMs are currently being built on a RedHat Version 6.2 system but should work on other 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:

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-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/rc.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.)

After installing the RPM file(s), the mysqld daemon should be 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 M.1 Installing a MySQL Binary Distribution.

2.1.2 Installing MySQL on Windows

The following instructions apply to precompiled binary distributions. If you download a source distribution, you will have to compile and install it yourself.

If you don't have a copy of the MySQL distribution, you should first download one from http://www.mysql.com/downloads/mysql-3.23.html.

If you plan to connect to MySQL from some other program, you will probably also need the MyODBC driver. You can find this at the MyODBC download page (http://www.mysql.com/downloads/api-myodbc.html).

To install either distribution, unzip it in some empty directory and run the Setup.exe program.

By default, MySQL-Windows is configured to be installed in `C:\mysql'. If you want to install MySQL elsewhere, install it in `C:\mysql' first, then move the installation to where you want it. If you do move MySQL, you must indicate where everything is located by supplying a --basedir option when you start the server. For example, if you have moved the MySQL distribution to `D:\programs\mysql', you must start mysqld like this: 

C:\> D:\programs\mysql\bin\mysqld --basedir D:\programs\mysql

Use mysqld --help to display all the options that mysqld understands!

With all newer MySQL versions, you can also create a `C:\my.cnf' file that holds any default options for the MySQL server. Copy the file `\mysql\my-xxxxx.cnf' to `C:\my.cnf' and edit it to suit your setup. Note that you should specify all paths with `/' instead of `\'. If you use `\', you need to specify it twice, because `\' is the escape character in MySQL. See section 4.1.2 my.cnf Option Files.

Starting with MySQL 3.23.38, the Windows distribution includes both the normal and the MySQL-Max binaries. The main benefit of using the normal mysqld.exe binary is that it's a little faster and uses less resources.

Here is a list of the different MySQL servers you can use:

mysqld Compiled with full debugging and automatic memory allocation checking, symbolic links, BDB and InnoDB tables.
mysqld-opt Optimized binary with no support for transactional tables.
mysqld-nt Optimized binary for NT with support for named pipes. You can run this version on Win98, but in this case no named pipes are created and you must have TCP/IP installed.
mysqld-max Optimized binary with support for symbolic links, BDB and InnoDB tables.
mysqld-max-nt Like mysqld-max, but compiled with support for named pipes.

All of the above binaries are optimized for the Pentium Pro processor but should work on any Intel processor >= i386.

NOTE: If you want to use InnoDB tables, there are certain startup options that must be specified in your `my.ini' file! See section 7.6.2 InnoDB startup options.

2.2 General Installation Issues

2.2.1 How to Get MySQL

Check the MySQL home page for information about the current version and for downloading instructions.

Our main download mirror is located at:

http://download.sourceforge.net/mirrors/mysql/

If you are interested in becoming a MySQL mirror site, you may anonymously rsync with: rsync://download.sourceforge.net/mysql/. Please send e-mail to webmaster@mysql.com notifying us of your mirror to be added to the list below.

If you have problems downloading from our main site, try using one of the mirrors listed below.

Please report bad or out-of-date mirrors to webmaster@mysql.com.

Europe:

North America:

South America:

Asia:

Africa:

2.2.2 Operating Systems Supported by MySQL

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:

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:

Based on the above 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 ok, 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 comparison above 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 optimizing for that particular platform. We are just stating our observations to help you make a decision on which platform to use MySQL on in your setup.

2.2.3 Which MySQL Version to Use

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:

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:

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:

An internal test suite
This is part of a production system for a customer. It has many tables with hundreds of megabytes of data.
The MySQL benchmark suite
This runs a range of common queries. It is also a test to see whether the latest batch of optimizations actually made the code faster. See section 5.1.4 The MySQL Benchmark Suite.
The crash-me test
This tries to determine what features the database supports and what its capabilities and limitations are. See section 5.1.4 The MySQL Benchmark Suite.

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.

2.2.4 Installation Layouts

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:

You can create your own binary installation from a compiled source distribution by executing the script `scripts/make_binary_distribution'.

2.2.5 How and When Updates Are Released

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 G 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.''

2.2.6 MySQL Binaries Compiled by MySQL AB

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 with scripts/make_binary_distribution and are configured with the following compilers and options:

SunOS 4.1.4 2 sun4c with 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
SunOS 5.5.1 (and above) sun4u with 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
SunOS 5.6 i86pc with gcc 2.8.1
CC=gcc CXX=gcc CXXFLAGS=-O3 ./configure --prefix=/usr/local/mysql --with-low-memory --with-extra-charsets=complex
Linux 2.0.33 i386 with pgcc 2.90.29 (egcs 1.0.3a)
CFLAGS="-O3 -mpentium -mstack-align-double" CXX=gcc CXXFLAGS="-O3 -mpentium -mstack-align-double -felide-constructors -fno-exceptions -fno-rtti" ./configure --prefix=/usr/local/mysql --enable-assembler --with-mysqld-ldflags=-all-static --with-extra-charsets=complex
Linux 2.2.x with x686 with 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-charset=complex
SCO 3.2v5.0.4 i386 with gcc 2.7-95q4
CC=gcc CXX=gcc CXXFLAGS=-O3 ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex
AIX 2 4 with gcc 2.7.2.2
CC=gcc CXX=gcc CXXFLAGS=-O3 ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex
OSF1 V4.0 564 alpha with gcc 2.8.1
CC=gcc CFLAGS=-O CXX=gcc CXXFLAGS=-O3 ./configure --prefix=/usr/local/mysql --with-low-memory --with-extra-charsets=complex
Irix 6.3 IP32 with gcc 2.8.0
CC=gcc CXX=gcc CXXFLAGS=-O3 ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex
BSDI BSD/OS 3.1 i386 with gcc 2.7.2.1
CC=gcc CXX=gcc CXXFLAGS=-O ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex
BSDI BSD/OS 2.1 i386 with gcc 2.7.2
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 configurations listed above 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 above configure lines and remove any -fomit-frame-pointer options.

2.3 Installing a MySQL Source Distribution

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 in 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:

If you are using a recent version of gcc, recent enough to understand -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-contructors 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 1.2.22.3 How to Report Bugs or Problems.

2.3.1 Quick Installation Overview

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 &

If you want have support for InnoDB tables, you should edit the /etc/my.cnf file and remove the # character before the parameters that starts with innodb_.... See section 4.1.2 my.cnf Option Files. See section 7.6.2 InnoDB startup options.

If you start from a source RPM, then do the following: 

shell> rpm --rebuild 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 the steps below, then proceed to section 2.4 Post-installation Setup and Testing, for post-installation initialization and testing:

  1. Pick the directory under which you want to unpack the distribution, and move into it.
  2. Obtain a distribution file from one of the sites listed in section 2.2.1 How to Get MySQL.
  3. If you are interested in using Berkeley DB tables with MySQL, you will need to obtain a patched version of the Berkeley DB source code. Please read the chapter on Berkeley DB tables before proceeding. See section 7.5 BDB or Berkeley_DB Tables. MySQL source distributions are provided as compressed tar archives and have names like `mysql-VERSION.tar.gz', where VERSION is a number like 3.23.41.
  4. Add a user and group for mysqld to run as: 
    shell> groupadd mysql
shell> useradd -g mysql mysql
    These 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.
  5. Unpack the distribution into the current directory: 
    shell> gunzip < /path/to/mysql-VERSION.tar.gz | tar xvf -
    This command creates a directory named `mysql-VERSION'.
  6. Change into the top-level directory of the unpacked distribution: 
    shell> cd mysql-VERSION
    Note that currently you must configure and build MySQL from this top-level directory. You can not build it in a different directory.
  7. Configure the release and compile everything: 
    shell> ./configure --prefix=/usr/local/mysql
shell> make
    When 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 1.2.22.3 How to Report Bugs or Problems. If the compile fails, see section 2.3.5 Problems Compiling?, for help with a number of common problems.
  8. Install everything: 
    shell> make install
    You might need to run this command as root.
  9. Create the MySQL grant tables (necessary only if you haven't installed MySQL before): 
    shell> scripts/mysql_install_db
    Note that MySQL versions older than Version 3.22.10 started the MySQL server when you run mysql_install_db. This is no longer true!
  10. Change ownership of binaries to 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/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.
  11. If you want to install support for the Perl DBI/DBD interface, see section M.2 Perl Installation Comments.
  12. If you would like MySQL to start automatically when you boot your machine, you can copy 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 initialize and test your distribution: 

shell> /usr/local/mysql/bin/safe_mysqld --user=mysql &

If that command fails immediately with mysqld daemon ended then 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.

See section 2.4 Post-installation Setup and Testing.

2.3.2 Applying Patches

Sometimes patches appear on the mailing list or are placed in the patches area of the MySQL Web site.

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 above 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.

2.3.3 Typical 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 B 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 below:

2.3.4 Installing from the Development Source Tree

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:

  1. Download BitKeeper from http://www.bitmover.com/cgi-bin/download.cgi. You will need Bitkeeper 2.0 or newer to access our repository.
  2. Follow the instructions to install it.
  3. After BitKeeper is installed, use this command if you want to clone the MySQL 3.23 branch: 
    shell> bk clone bk://work.mysql.com:7000 mysql
    To clone the 4.0 branch, use this command instead: 
    shell> bk clone bk://work.mysql.com:7001 mysql-4.0
    The initial download of the source tree may take a while, depending on the speed of your connection; be patient.
  4. You will need GNU autoconf, automake, libtool, and m4 to run the next set of commands. If you get some strange error during this stage, check that you really have libtool installed! 
    shell> cd mysql
shell> bk -r edit
shell> aclocal; autoheader; autoconf;  automake;
shell> ./configure  # Add your favorite options here
shell> make
    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 removing flags that are Pentium-specific.
  5. When the build is done, run 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, tcp-port, and unix-socket-path options than those used for your production server.
  6. Play hard with your new installation and try to make the new features crash. Start by running make test. See section 9.3.2 MySQL Test Suite.
  7. If you have gotten to the 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 your shell can find them.
  8. After the initial bk clone operation to get the source tree, you should run bk pull periodically to get the updates.
  9. You can examine the change history for the tree with all the diffs by using 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 email 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.
  10. BitKeeper has a nice help utility that you can access via bk helptool.

2.3.5 Problems Compiling?

All MySQL programs compile cleanly for us with no warnings on Solaris 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 list below.

The solution to many problems involves reconfiguring. If you do need to reconfigure, take note of the following:

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 list below describes some of the problems compiling MySQL that have been found to occur most often:

2.3.6 MIT-pthreads Notes

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 2.2.2 Operating Systems Supported by MySQL.

2.4 Post-installation Setup and Testing

Once you've installed MySQL (from either a binary or source distribution), you need to initialize 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> ./bin/mysql_install_db
shell> ./bin/safe_mysqld --user=mysql &

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 below 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 below:

  1. If necessary, start the 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_db
    Typically, 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'
    The above 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 user can read and write files in the database directory. Instructions for running MySQL as an unprivileged user are given in section A.8 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: For more information about these alternatives, see section 4.3.4 Setting Up the Initial MySQL Privileges.
  2. Start the MySQL server like this: 
    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.
  3. Use 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 variables
    The output from mysqladmin version varies slightly depending on your platform and version of MySQL, but should be similar to that shown below: 
    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: 16773K
    To get a feeling for what else you can do with BINDIR/mysqladmin, invoke it with the --help option.
  4. Verify that you can shut down the server: 
    shell> BINDIR/mysqladmin -u root shutdown
  5. Verify that you can restart the server. Do this using 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.
  6. Run some simple tests to verify that the server is working. The output should be similar to what is shown below: 
    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-tests
    If 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.tst
    The expected results are shown in the `./tests/auto_increment.res' file.

2.4.1 Problems Running 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
You may find that 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 ended
In 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 1.2.22.3 How to Report Bugs or Problems.
There is already a mysqld daemon running
In this case, you probably don't have to run mysql_install_db at all. You have to run mysql_install_db only once, when you install MySQL the first time.
Installing a second mysqld daemon doesn't work when one daemon is running
This can happen when you already have an existing MySQL installation, but want to put a new installation in a different place (for example, for testing, or perhaps you simply want to run two installations at the same time). Generally the problem that occurs when you try to run the second server is that it tries to use the same socket and port as the old one. In this case you will get the error message: 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.
You don't have write access to `/tmp'
If you don't have write access to create a socket file at the default place (in `/tmp') or permission to create temporary files in `/tmp,' you will get an error when running 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_PORT
`some_tmp_dir' should be the path to some directory for which you have write permission. See section B 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
If you are running RedHat Version 5.0 with a version of 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://www.mysql.com/documentation/. 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 mysql
From 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.

2.4.2 Problems Starting the MySQL Server

If you are going to use tables that support transactions (BDB, InnoDB), 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 three ways:

When the mysqld daemon starts up, it changes 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, `\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

If you find 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 these. 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 RETURN 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 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 H.1.2 Creating trace files.

If you are using InnoDB tables, refer to the InnoDB-specific startup options. See section 7.6.2 InnoDB startup options.

If you are using BDB (Berkeley DB) tables, you should familiarize yourself with the different BDB specific startup options. See section 7.5.3 BDB startup options.

2.4.3 Starting and Stopping MySQL Automatically

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 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 take down the server manually by executing mysqladmin shutdown.

You might want to add these start and stop commands to the appropriate places in your `/etc/rc*' files when you start using MySQL for production applications. Note that if you modify mysql.server, then upgrade MySQL sometime, your modified version will be overwritten, so you should make a copy of your edited version that you can reinstall.

If your system uses `/etc/rc.local' to start external scripts, you should append 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=/tmp/mysqld.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.

2.5 Upgrading/Downgrading MySQL

You can always move the MySQL form and data files 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 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.

2.5.1 Upgrading From Version 3.22 to Version 3.23

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 lists tell what you have to watch out for when upgrading to Version 3.23:

2.5.2 Upgrading from Version 3.21 to Version 3.22

Nothing that affects compatibility has changed between Version 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.

2.5.3 Upgrading from Version 3.20 to Version 3.21

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:

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, 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:

2.5.4 Upgrading to Another Architecture

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 commands shown below, 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.

2.6 Operating System Specific Notes

2.6.1 Linux Notes (All Linux Versions)

The notes below 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 text below, 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 2GB 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/Linux.

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 to upgrade to Linux 2.4 ASAP! 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 you to 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 you have a problem with that 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 forwards, you can check the number of allocated file handlers 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 16M of memory, you should add something like the following in your boot script (`/etc/rc/boot.local' on SuSE): 

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 above from the command line as root, but in this case your old limits will be used next time your computer reboots.

You should also add /etc/my.cnf: 

[safe_mysqld]
open-files-limit=8192

The above 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 thread 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" behavior 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" behavior by setting a reasonable value for the max_connections variable.

If you build MySQL yourself and do not what 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 2GB 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 penalizes 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 here (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 query throughput all the way up to 1000 clients, and 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, linuxthreads-2.1-patch to correct this behavior.

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 behavior with a patch, available here. 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.2 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-sizes=1000000. See section 4.7.2 safe_mysqld, the wrapper around mysqld.

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-sizes=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:

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

2.6.1.1 Linux Notes for Binary Distributions

MySQL needs at least Linux Version 2.0.

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:

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.

2.6.1.2 Linux x86 Notes

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 or not there are any updates! The glibc 2.0.7-19 and 2.0.7-29 RPMs are known to work.

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 below 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'

In Debian GNU/Linux, if you want MySQL to start automatically when the system boots, do the following: 

shell> cp support-files/mysql.server /etc/init.d/mysql.server
shell> /usr/sbin/update-rc.d mysql.server defaults 99

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

2.6.1.3 Linux SPARC Notes

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.

2.6.1.4 Linux Alpha Notes

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. The main thing we haven't yet had time to test is how things works with many concurrent users.

When we compiled the standard MySQL binary we are using SuSE 6.4, kernel 2.2.13-SMP, Compaq C compiler (V6.2-504) and Compaq C++ compiler (V6.3-005) on a Comaq 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 the configure line optimized the binary for the current CPU; This means you can only use our binary if you have an Alpha EV6 processor. We also compile statically to avoid library problems. 

CC=ccc CFLAGS="-fast" CXX=cxx CXXFLAGS="-fast -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:

2.6.1.5 Linux PowerPC Notes

MySQL should work on MkLinux with the newest glibc package (tested with glibc 2.0.7).

2.6.1.6 Linux MIPS Notes

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).

2.6.1.7 Linux IA64 Notes

To get MySQL to compile on Linux Ia64, we had to do the following (we assume that this will be easier when next gcc version for ia64 is released).

Using gcc-2.9-final: 

CFLAGS="-O2" CXX=gcc CXXFLAGS="-O2 -felide-constructors -fno-exceptions -fno-rtti" ./configure --prefix=/usr/local/mysql --enable-assembler --with-mysqld-ldflags=-all-static --disable-shared --with-extra-charsets=complex

After make you will get an error that sql/opt_range.cc will not compile (internal compiler error). To fix this, go to the sql directory and type make again. Copy the compile line, but change -O2 to -O0. The file should now compile.

Now you can do: 

cd ..
make
make_install

and mysqld should be ready to run.

2.6.2 Windows Notes

This section describes installation and use of MySQL on Windows. This information is also provided in the `README' file that comes with the MySQL Windows distribution.

2.6.2.1 Starting MySQL on Windows 95 or Windows 98

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 Win95 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/. Win98 has the new Winsock 2 library, so the above doesn't apply for Win98.

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

Note that Win95 and Win98 don't support creation of named pipes. On Win95 and Win98, you can only use named pipes to connect to a remote MySQL server running on a Windows NT server host. (The MySQL server must also support named pipes, of course. For example, using mysqld-opt under NT 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 H.1.2 Creating trace files.

2.6.2.2 Starting MySQL on Windows NT or Windows 2000

The Win95/Win98 section also applies to MySQL on NT/Win2000, with the following differences:

To get MySQL to work with TCP/IP on NT, you must install service pack 3 (or newer)!

Note that everything in the following that applies for NT also applies for Win2000!

For NT/Win2000, the server name is mysqld-nt. Normally you should install MySQL as a service on NT/Win2000: 

C:\> C:\mysql\bin\mysqld-nt --install

or 

C:\> C:\mysql\bin\mysqld-max-nt --install

(Under Windows NT, you can actually install any of the server binaries as a service, but only those having names that end with -nt.exe provide support for named pipes.)

You can start and stop the MySQL service with these commands: 

C:\> NET START mysql
C:\> NET STOP mysql

Note that in this case you can't use any other options for mysqld-nt!

You can also run mysqld-nt as a stand-alone program on NT if you need to start mysqld-nt with any options! If you start mysqld-nt without options on NT, mysqld-nt tries to start itself as a service with the default service options. If you have stopped mysqld-nt, you have to start it with NET START mysql.

The service is installed with the name MySQL. Once installed, it must be started using the Services Control Manager (SCM) Utility found in the Control Panel, or by using the NET START MySQL command. If any options are desired, they must be specified as ``Startup parameters'' in the SCM utility before you start the MySQL service. Once running, mysqld-nt can be stopped using mysqladmin, or from the SCM utility or by using the command NET STOP MySQL. If you use SCM to stop mysqld-nt, there is a strange message from SCM about mysqld shutdown normally. When run as a service, mysqld-nt has no access to a console and so no messages can be seen.

On NT you can get the following service error messages:

Permission Denied Means that it cannot find mysqld-nt.exe.
Cannot Register Means that the path is incorrect.
Failed to install service. Means that the service is already installed or that the Service Control Manager is in bad state.

If you have problems installing mysqld-nt as a service, try starting it with the full path: 

C:\> C:\mysql\bin\mysqld-nt --install

If this doesn't work, you can get mysqld-nt to start properly by fixing the path in the registry!

If you don't want to start mysqld-nt as a service, you can start it as follows: 

C:\> C:\mysql\bin\mysqld-nt --standalone

or 

C:\> C:\mysql\bin\mysqld --standalone --debug

The last version gives you a debug trace in `C:\mysqld.trace'. See section H.1.2 Creating trace files.

2.6.2.3 Running MySQL on Windows

MySQL supports TCP/IP on all Windows platforms and named pipes on NT. The default is to use named pipes for local connections on NT 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, try named pipes first; if that doesn't work, use TCP/IP. On Win95/Win98, 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.

You can test whether or not 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 Win95/Win98, 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 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:
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 can be used by anyone to access the test database, 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 OPTION password'. The fix is in to upgrade to the current MySQL version, which is 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.

2.6.2.4 Connecting to a Remote MySQL from Windows with SSH

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):

You should now have an ODBC connection to MySQL, encrypted using SSH.

2.6.2.5 Splitting Data Across Different Disks on Windows

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.

2.6.2.6 Compiling MySQL Clients on Windows

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!

2.6.2.7 MySQL-Windows Compared to Unix MySQL

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:

Win95 and threads
Win95 leaks about 200 bytes of main memory for each thread creation. Each connection in MySQL creates a new thread, so you shouldn't run mysqld for an extended time on Win95 if your server handles many connections! WinNT and Win98 don't suffer from this bug.
Concurrent reads
MySQL depends on the 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 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 as on Unix.
Blocking read
MySQL uses a blocking read for each connection. This means that: We plan to fix this problem when our Windows developers have figured out a nice workaround.
UDF functions
For the moment, MySQL-Windows does not support user-definable functions.
DROP DATABASE
You can't drop a database that is in use by some thread.
Killing MySQL from the task manager
You can't kill MySQL from the task manager or with the shutdown utility in Win95. You must take it down with mysqladmin shutdown.
Case-insensitive names
Filenames are case insensitive on Windows, so database and table names are also case insensitive in MySQL for Windows. The only restriction is that database and table names must be specified using the same case throughout a given statement. See section 6.1.3 Case Sensitivity in Names.
The `\' directory character
Pathname components in Win95 are separated by the `\' character, which is also the escape character in MySQL. If you are using 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
If you use a MySQL 3.22 version on NT with the newest mysql-clients you will get the following 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 = localhost
Access denied for user error
If you get the 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
While you are executing an 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
The MERGE handler does its table mapping hidden from 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.

Here are some open issues for anyone who might want to help us with the Windows release:

Other Windows-specific issues are described in the `README' file that comes with the MySQL-Windows distribution.

2.6.3 Solaris Notes

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/.

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 a ultra sparc, you can get 4 % more performance by adding "-mcpu=v8 -Wa,-xarch=v8plusa" to CFLAGS and CXXFLAGS.

If you have the Sun Workshop (SunPro) 4.2 (or newer) compiler, you can run configure like this: 

CC=cc CFLAGS="-Xa -fast -xO4 -native -xstrconst -mt" \
CXX=CC CXXFLAGS="-noex -xO4 -mt" \
./configure --prefix=/usr/local/mysql --enable-assembler

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 below 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 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'

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. 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:

When using the --with-libwrap configure option, you must also include the libraries that `libwrap.a' needs: 

--with-libwrap="/opt/NUtcpwrapper-7.6/lib/libwrap.a -lnsl -lsocket

If you have problems with configure trying to link with -lz and you don't have zlib installed, you have two options:

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'.

2.6.3.1 Solaris 2.7/2.8 Notes

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:

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:

2.6.3.2 Solaris x86 Notes

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 H.1.3 Debugging mysqld under gdb.

2.6.4 BSD Notes

2.6.4.1 FreeBSD Notes

FreeBSD 3.x is recommended for running MySQL since the thread package is much more integrated.

The easiest and therefor 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 Makefiles 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

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.11 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 get problems with the current date in MySQL, setting the TZ variable will probably help. See section B Environment Variables.

To get a secure and stable system you should only use FreeBSD kernels that are marked -STABLE.

2.6.4.2 NetBSD notes

To compile on NetBSD you need GNU make. Otherwise the compile will crash when make tries to run lint on C++ files.

2.6.4.3 OpenBSD Notes

2.6.4.4 OpenBSD 2.5 Notes

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

2.6.4.5 OpenBSD 2.8 Notes

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.

2.6.4.6 BSD/OS Notes

2.6.4.7 BSD/OS Version 2.x Notes

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 B Environment Variables.

2.6.4.8 BSD/OS Version 3.x Notes

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.

2.6.4.9 BSD/OS Version 4.x Notes

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 ok).

2.6.5 Mac OS X Notes

2.6.5.1 Mac OS X Public Beta

MySQL should work without any problems on Mac OS X Public Beta (Darwin). You don't need the pthread patches for this OS!

2.6.5.2 Mac OS X Server

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 Rhapsody 5.5 with the following configure line: 

CC=gcc CFLAGS="-O2 -fomit-frame-pointer" CXX=gcc CXXFLAGS="-O2 -fomit-frame-pointer" ./configure --prefix=/usr/local/mysql "--with-comment=Official MySQL binary" --with-extra-charsets=complex  --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'

2.6.6 Other Unix Notes

2.6.6.1 HP-UX Notes for Binary Distributions

Some of the binary distributions of MySQL for HP-UX is 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 below, where /path/to/depot is the full pathname of the depot file:

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.

2.6.6.2 HP-UX Version 10.20 Notes

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 optimization flags (like -O6) as this may not be safe on HP-UX.

Note that MIT-pthreads can't be compiled with the HP-UX compiler because it can't compile .S (assembler) files.

The following configure line should work: 

CFLAGS="-DHPUX -I/opt/dce/include" CXXFLAGS="-DHPUX -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

If you are compiling gcc 2.95 yourself, you should NOT link it with the DCE libraries (libdce.a or libcma.a) if you want to compile MySQL with MIT-pthreads. If you mix the DCE and MIT-pthreads packages you will get a mysqld to which you cannot connect. Remove the DCE libraries while you compile gcc 2.95!

2.6.6.3 HP-UX Version 11.x Notes

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 a problem that one gets 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

Here is some information that a HP-UX Version 11.x user sent us about compiling MySQL with HP-UX:x compiler: 

 Environment:
      proper compilers.
         setenv CC cc
         setenv CXX aCC
      flags
         setenv CFLAGS -D_REENTRANT
         setenv CXXFLAGS -D_REENTRANT
         setenv CPPFLAGS -D_REENTRANT
     % aCC -V
     aCC: HP ANSI C++ B3910B X.03.14.06
     % cc -V /tmp/empty.c
     cpp.ansi: HP92453-01 A.11.02.00 HP C Preprocessor (ANSI)
     ccom: HP92453-01 A.11.01.00 HP C Compiler
     cc: "/tmp/empty.c", line 1: warning 501: Empty source file.

  configuration:
     ./configure  --with-pthread        \
     --prefix=/source-control/mysql     \
     --with-named-thread-libs=-lpthread \
     --with-low-memory

    added '#define _CTYPE_INCLUDED' to include/m_ctype.h. This
    symbol is the one defined in HP's /usr/include/ctype.h:

     /* Don't include std ctype.h when this is included */
     #define _CTYPE_H
     #define __CTYPE_INCLUDED
     #define _CTYPE_INCLUDED
     #define _CTYPE_USING   /* Don't put names in global namespace. */

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.

2.6.6.4 IBM-AIX notes

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 LDLFAGS="-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://www.rs6000.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

2.6.6.5 SunOS 4 Notes

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.

2.6.6.6 Alpha-DEC-UNIX Notes (Tru64)

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 -speculate all -arch host"
CXX="cxx -pthread"
CXXFLAGS="-O4 -ansi_alias -ansi_args -fast -inline speed -speculate all -arch host"
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

2.6.6.7 Alpha-DEC-OSF1 Notes

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 OSF1 V4.0D and compiler "DEC C V5.6-071 on Digital Unix V4.0 (Rev. 878)" the compiler had some strange behavior (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 OSF1, 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.

2.6.6.8 SGI Irix Notes

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 --with-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-berkeley-db --with-innodb \
--with-libwrap=/usr/local --with-named-curses-libs=/usr/local/lib/libncurses.a

2.6.6.9 SCO Notes

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)
  1. For OpenServer 5.0.X you need to use GDS in Skunkware 95 (95q4c). This is necessary because GNU gcc 2.7.2 in Skunkware 97 does not have GNU as. You can also use egcs 1.1.2 or newer http://www.egcs.com/. If you are using egcs 1.1.2 you have to execute the following command: 
    shell> cp -p /usr/include/pthread/stdtypes.h /usr/local/lib/gcc-lib/i386-pc-sco3.2v5.0.5/egcs-2.91.66/include/pthread/
  2. You need the port of GCC 2.5.x for this product and the Development system. They are required on this version of SCO Unix. You cannot just use the GCC Dev system.
  3. You should get the FSU Pthreads package and install it first. This can be found at http://www.cs.wustl.edu/~schmidt/ACE_wrappers/FSU-threads.tar.gz. You can also get a precompiled package from http://www.mysql.com/Downloads/SCO/FSU-threads-3.5c.tar.gz.
  4. FSU Pthreads can be compiled with SCO Unix 4.2 with tcpip. Or OpenServer 3.0 or Open Desktop 3.0 (OS 3.0 ODT 3.0), with the SCO Development System installed using a good port of GCC 2.5.x ODT or OS 3.0 you will need a good port of GCC 2.5.x There are a lot of problems without a good port. The port for this product requires the SCO Unix Development system. Without it, you are missing the libraries and the linker that is needed.
  5. To build FSU Pthreads on your system, do the following:
    1. Run ./configure in the `threads/src' directory and select the SCO OpenServer option. This command copies `Makefile.SCO5' to `Makefile'.
    2. Run make.
    3. To install in the default `/usr/include' directory, login as root, then cd to the `thread/src' directory, and run make install.
  6. Remember to use GNU make when making MySQL.
  7. If you don't start 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.
  8. With SCO 3.2V5.0.5, you should use FSU Pthreads version 3.5c or newer. You should also use gcc 2.95.2 or newer! The following configure command should work: 
    shell> ./configure --prefix=/usr/local/mysql --disable-shared
  9. With SCO 3.2V4.2, you should use FSU Pthreads version 3.5c or newer. The following 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.

SCO development notes:

If you want to install DBI on 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.

2.6.6.10 SCO Unixware Version 7.0 Notes

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.

2.6.7 OS/2 Notes

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";

2.6.8 BeOS Notes

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.

2.6.9 Novell Netware Notes

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.

3 Introduction to MySQL: A MySQL Tutorial

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.

3.1 Connecting to and Disconnecting from the Server

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.

3.2 Entering Queries

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 familiarize 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 below following the mysql> prompt and hit the RETURN key: 

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:

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 summarizes 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 realizing 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 hit RETURN 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.

3.3 Creating and Using a Database

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 or Zip format.

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.

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.

3.3.1 Creating and Selecting a Database

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.

3.3.2 Creating a Table

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.)

Animal sex can be represented in a variety of ways, for example, "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.

3.3.3 Loading Data into a Table

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 below. (Observe that MySQL expects dates in YYYY-MM-DD format; this may be different than 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 1989-08-31 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):

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.

3.3.4 Retrieving Information from a Table

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.

3.3.4.1 Selecting All Data

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 data file: 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 are least a couple of ways to fix this:

As shown above, it is easy to retrieve an entire table. But typically you don't want to do that, particularly when the table becomes large. Instead, you're usually more interested in answering a particular question, in which case you specify some constraints on the information you want. Let's look at some selection queries in terms of questions about your pets that they answer.

3.3.4.2 Selecting Particular Rows

You can select only particular rows from your table. For example, if you want to verify the change that you made to Bowser's birth date, select Bowser's record like this: 

mysql> SELECT * FROM pet WHERE name = "Bowser";
+--------+-------+---------+------+------------+------------+
| name   | owner | species | sex  | birth      | death      |
+--------+-------+---------+------+------------+------------+
| Bowser | Diane | dog     | m    | 1989-08-31 | 1995-07-29 |
+--------+-------+---------+------+------------+------------+

The output confirms that the year is correctly recorded now as 1989, not 1998.

String comparisons are normally case insensitive, so you can specify the name as "bowser", "BOWSER", etc. The query result will be the same.

You can specify conditions on any column, not just name. For example, if you want to know which animals were born after 1998, test the birth column: 

mysql> SELECT * FROM pet WHERE birth >= "1998-1-1";
+----------+-------+---------+------+------------+-------+
| name     | owner | species | sex  | birth      | death |
+----------+-------+---------+------+------------+-------+
| Chirpy   | Gwen  | bird    | f    | 1998-09-11 | NULL  |
| Puffball | Diane | hamster | f    | 1999-03-30 | NULL  |
+----------+-------+---------+------+------------+-------+

You can combine conditions, for example, to locate female dogs: 

mysql> SELECT * FROM pet WHERE species = "dog" AND sex = "f";
+-------+--------+---------+------+------------+-------+
| name  | owner  | species | sex  | birth      | death |
+-------+--------+---------+------+------------+-------+
| Buffy | Harold | dog     | f    | 1989-05-13 | NULL  |
+-------+--------+---------+------+------------+-------+

The preceding query uses the AND logical operator. There is also an OR operator: 

mysql> SELECT * FROM pet WHERE species = "snake" OR species = "bird";
+----------+-------+---------+------+------------+-------+
| name     | owner | species | sex  | birth      | death |
+----------+-------+---------+------+------------+-------+
| Chirpy   | Gwen  | bird    | f    | 1998-09-11 | NULL  |
| Whistler | Gwen  | bird    | NULL | 1997-12-09 | NULL  |
| Slim     | Benny | snake   | m    | 1996-04-29 | NULL  |
+----------+-------+---------+------+------------+-------+

AND and OR may be intermixed. If you do that, it's a good idea to use parentheses to indicate how conditions should be grouped: 

mysql> SELECT * FROM pet WHERE (species = "cat" AND sex = "m")
    -> OR (species = "dog" AND sex = "f");
+-------+--------+---------+------+------------+-------+
| name  | owner  | species | sex  | birth      | death |
+-------+--------+---------+------+------------+-------+
| Claws | Gwen   | cat     | m    | 1994-03-17 | NULL  |
| Buffy | Harold | dog     | f    | 1989-05-13 | NULL  |
+-------+--------+---------+------+------------+-------+

3.3.4.3 Selecting Particular Columns

If you don't want to see entire rows from your table, just name the columns in which you're interested, separated by commas. For example, if you want to know when your animals were born, select the name and birth columns: 

mysql> SELECT name, birth FROM pet;
+----------+------------+
| name     | birth      |
+----------+------------+
| Fluffy   | 1993-02-04 |
| Claws    | 1994-03-17 |
| Buffy    | 1989-05-13 |
| Fang     | 1990-08-27 |
| Bowser   | 1989-08-31 |
| Chirpy   | 1998-09-11 |
| Whistler | 1997-12-09 |
| Slim     | 1996-04-29 |
| Puffball | 1999-03-30 |
+----------+------------+

To find out who owns pets, use this query: 

mysql> SELECT owner FROM pet;
+--------+
| owner  |
+--------+
| Harold |
| Gwen   |
| Harold |
| Benny  |
| Diane  |
| Gwen   |
| Gwen   |
| Benny  |
| Diane  |
+--------+

However, notice that the query simply retrieves the owner field from each record, and some of them appear more than once. To minimize the output, retrieve each unique output record just once by adding the keyword DISTINCT: 

mysql> SELECT DISTINCT owner FROM pet;
+--------+
| owner  |
+--------+
| Benny  |
| Diane  |
| Gwen   |
| Harold |
+--------+

You can use a WHERE clause to combine row selection with column selection. For example, to get birth dates for dogs and cats only, use this query: 

mysql> SELECT name, species, birth FROM pet
    -> WHERE species = "dog" OR species = "cat";
+--------+---------+------------+
| name   | species | birth      |
+--------+---------+------------+
| Fluffy | cat     | 1993-02-04 |
| Claws  | cat     | 1994-03-17 |
| Buffy  | dog     | 1989-05-13 |
| Fang   | dog     | 1990-08-27 |
| Bowser | dog     | 1989-08-31 |
+--------+---------+------------+

3.3.4.4 Sorting Rows

You may have noticed in the preceding examples that the result rows are displayed in no particular order. However, it's often easier to examine query output when the rows are sorted in some meaningful way. To sort a result, use an ORDER BY clause.

Here are animal birthdays, sorted by date: 

mysql> SELECT name, birth FROM pet ORDER BY birth;
+----------+------------+
| name     | birth      |
+----------+------------+
| Buffy    | 1989-05-13 |
| Bowser   | 1989-08-31 |
| Fang     | 1990-08-27 |
| Fluffy   | 1993-02-04 |
| Claws    | 1994-03-17 |
| Slim     | 1996-04-29 |
| Whistler | 1997-12-09 |
| Chirpy   | 1998-09-11 |
| Puffball | 1999-03-30 |
+----------+------------+

To sort in reverse order, add the DESC (descending) keyword to the name of the column you are sorting by: 

mysql> SELECT name, birth FROM pet ORDER BY birth DESC;
+----------+------------+
| name     | birth      |
+----------+------------+
| Puffball | 1999-03-30 |
| Chirpy   | 1998-09-11 |
| Whistler | 1997-12-09 |
| Slim     | 1996-04-29 |
| Claws    | 1994-03-17 |
| Fluffy   | 1993-02-04 |
| Fang     | 1990-08-27 |
| Bowser   | 1989-08-31 |
| Buffy    | 1989-05-13 |
+----------+------------+

You can sort on multiple columns. For example, to sort by type of animal, then by birth date within animal type with youngest animals first, use the following query: 

mysql> SELECT name, species, birth FROM pet ORDER BY species, birth DESC;
+----------+---------+------------+
| name     | species | birth      |
+----------+---------+------------+
| Chirpy   | bird    | 1998-09-11 |
| Whistler | bird    | 1997-12-09 |
| Claws    | cat     | 1994-03-17 |
| Fluffy   | cat     | 1993-02-04 |
| Fang     | dog     | 1990-08-27 |
| Bowser   | dog     | 1989-08-31 |
| Buffy    | dog     | 1989-05-13 |
| Puffball | hamster | 1999-03-30 |
| Slim     | snake   | 1996-04-29 |
+----------+---------+------------+

Note that the DESC keyword applies only to the column name immediately preceding it (birth); species values are still sorted in ascending order.

3.3.4.5 Date Calculations

MySQL provides several functions that you can use to perform calculations on dates, for example, to calculate ages or extract parts of dates.

To determine how many years old each of your pets is, compute age as the difference between the birth date and the current date. Do this by converting the two dates to days, take the difference, and divide by 365 (the number of days in a year): 

mysql> SELECT name, (TO_DAYS(NOW())-TO_DAYS(birth))/365 FROM pet;
+----------+-------------------------------------+
| name     | (TO_DAYS(NOW())-TO_DAYS(birth))/365 |
+----------+-------------------------------------+
| Fluffy   |                                6.15 |
| Claws    |                                5.04 |
| Buffy    |                                9.88 |
| Fang     |                                8.59 |
| Bowser   |                                9.58 |
| Chirpy   |                                0.55 |
| Whistler |                                1.30 |
| Slim     |                                2.92 |
| Puffball |                                0.00 |
+----------+-------------------------------------+

Although the query works, there are some things about it that could be improved. First, the result could be scanned more easily if the rows were presented in some order. Second, the heading for the age column isn't very meaningful.

The first problem can be handled by adding an ORDER BY name clause to sort the output by name. To deal with the column heading, provide a name for the column so that a different label appears in the output (this is called a column alias): 

mysql> SELECT name, (TO_DAYS(NOW())-TO_DAYS(birth))/365 AS age
    -> FROM pet ORDER BY name;
+----------+------+
| name     | age  |
+----------+------+
| Bowser   | 9.58 |
| Buffy    | 9.88 |
| Chirpy   | 0.55 |
| Claws    | 5.04 |
| Fang     | 8.59 |
| Fluffy   | 6.15 |
| Puffball | 0.00 |
| Slim     | 2.92 |
| Whistler | 1.30 |
+----------+------+

To sort the output by age rather than name, just use a different ORDER BY clause: 

mysql>  SELECT name, (TO_DAYS(NOW())-TO_DAYS(birth))/365 AS age
    ->  FROM pet ORDER BY age;
+----------+------+
| name     | age  |
+----------+------+
| Puffball | 0.00 |
| Chirpy   | 0.55 |
| Whistler | 1.30 |
| Slim     | 2.92 |
| Claws    | 5.04 |
| Fluffy   | 6.15 |
| Fang     | 8.59 |
| Bowser   | 9.58 |
| Buffy    | 9.88 |
+----------+------+

A similar query can be used to determine age at death for animals that have died. You determine which animals these are by checking whether or not the death value is NULL. Then, for those with non-NULL values, compute the difference between the death and birth values: 

mysql>  SELECT name, birth, death, (TO_DAYS(death)-TO_DAYS(birth))/365 AS age
    ->  FROM pet WHERE death IS NOT NULL ORDER BY age;
+--------+------------+------------+------+
| name   | birth      | death      | age  |
+--------+------------+------------+------+
| Bowser | 1989-08-31 | 1995-07-29 | 5.91 |
+--------+------------+------------+------+

The query uses death IS NOT NULL rather than death != NULL because NULL is a special value. This is explained later. See section 3.3.4.6 Working with NULL Values.

What if you want to know which animals have birthdays next month? For this type of calculation, year and day are irrelevant; you simply want to extract the month part of the birth column. MySQL provides several date-part extraction functions, such as YEAR(), MONTH(), and DAYOFMONTH(). MONTH() is the appropriate function here. To see how it works, run a simple query that displays the value of both birth and MONTH(birth): 

mysql> SELECT name, birth, MONTH(birth) FROM pet;
+----------+------------+--------------+
| name     | birth      | MONTH(birth) |
+----------+------------+--------------+
| Fluffy   | 1993-02-04 |            2 |
| Claws    | 1994-03-17 |            3 |
| Buffy    | 1989-05-13 |            5 |
| Fang     | 1990-08-27 |            8 |
| Bowser   | 1989-08-31 |            8 |
| Chirpy   | 1998-09-11 |            9 |
| Whistler | 1997-12-09 |           12 |
| Slim     | 1996-04-29 |            4 |
| Puffball | 1999-03-30 |            3 |
+----------+------------+--------------+

Finding animals with birthdays in the upcoming month is easy, too. Suppose the current month is April. Then the month value is 4 and you look for animals born in May (month 5) like this: 

mysql> SELE