The MySQL (R) software delivers a very fast, multi-threaded, multi-user, and robust SQL (Structured Query Language) database server. MySQL Server is intended for mission-critical, heavy-load production systems as well as for embedding into mass-deployed software. MySQL is a registered trademark of MySQL AB.
The MySQL software is Dual Licensed. Users can choose to use the MySQL software as an Open Source/Free Software product under the terms of the GNU General Public License (http://www.fsf.org/licenses/) or can purchase a standard commercial license from MySQL AB. See section 1.4 MySQL Support and Licensing.
The MySQL Web site (http://www.mysql.com/) provides the latest information about the MySQL software.
The following list describes some sections of particular interest in this manual:
Important:
Reports of errors (often called ``bugs''), as well as questions and comments, should be sent to the general MySQL mailing list. See section 1.7.1.1 The MySQL Mailing Lists. See section 1.7.1.3 How to Report Bugs or Problems.
The mysqlbug script should be used to generate bug reports on Unix.
(Windows distributions contain a file named `mysqlbug.txt' in the base
directory that can be used as a template for a bug report.)
For source distributions, the mysqlbug script can be found in the
`scripts' directory. For binary distributions, mysqlbug
can be found in the `bin' directory (`/usr/bin' for the
MySQL-server RPM package).
If you have found a sensitive security bug in MySQL Server, please let us know immediately by sending an email message to security@mysql.com.
This is the Reference Manual for the MySQL Database System. It documents MySQL up to Version 5.0.1-alpha, but is also applicable for older versions of the MySQL software (such as 3.23 or 4.0-production) because functional changes are indicated with reference to a version number.
Because this manual serves as a reference, it does not provide general instruction on SQL or relational database concepts. It also will not teach you how to use your operating system or command-line interpreter.
The MySQL Database Software is under constant development, and the Reference Manual is updated frequently as well. The most recent version of the manual is available online in searchable form at http://dev.mysql.com/doc/. Other formats also are available, including HTML, PDF, and Windows CHM versions.
The primary document is the Texinfo file.
The HTML version is produced automatically using a modified version of
texi2html.
The plain text and Info versions are produced with makeinfo.
The PostScript version is produced using texi2dvi and dvips.
The PDF version is produced with pdftex.
If you have any suggestions concerning additions or corrections to this manual, please send them to the documentation team at docs@mysql.com.
This manual was initially written by David Axmark and Michael ``Monty'' Widenius. It is now maintained by the MySQL Documentation Team, consisting of Arjen Lentz, Paul DuBois, and Stefan Hinz. For the many other contributors, see section B Credits.
The copyright (2004) to this manual is owned by the Swedish company MySQL AB. See section 1.4.2 Copyrights and Licenses Used by MySQL. MySQL and the MySQL logo are (registered) trademarks of MySQL AB. Other trademarks and registered trademarks referred to in this manual are the property of their respective owners, and are used for identification purposes only.
This manual uses certain typographical conventions:
constant
mysqladmin works, invoke it with the
--help option.''
When commands are shown that are meant to be executed from within 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 statement that you execute from the
mysql client program:
shell> type a shell command here mysql> type a mysql statement here
The ``shell'' is your command interpreter. On Unix, this is typically a
program such as sh or csh. On Windows, the equivalent program is
command.com or cmd.exe, typically run in a console window.
When you enter a command or statement shown in an example, do not type the prompt shown in the example.
Database, table, and column names must often be substituted into statements. To indicate that such substitution is necessary, this manual uses db_name, tbl_name, and col_name. For example, you might see a statement like this:
mysql> SELECT col_name FROM db_name.tbl_name;
This means that if you were to enter a similar statement, you would supply your own database, table, and column names, perhaps like this:
mysql> SELECT author_name FROM biblio_db.author_list;
SQL keywords are not case sensitive and may be written in uppercase or lowercase. This manual uses uppercase.
In syntax descriptions, square brackets (`[' and `]') are used
to indicate optional words or clauses. For example, in the following
statement, IF EXISTS is optional:
DROP TABLE [IF EXISTS] tbl_name
When a syntax element consists of a number of alternatives, the alternatives are separated by vertical bars (`|'). When one member from a set of choices may be chosen, the alternatives are listed within square brackets (`[' and `]'):
TRIM([[BOTH | LEADING | TRAILING] [remstr] FROM] str)
When one member from a set of choices must be chosen, the alternatives are listed within braces (`{' and `}'):
{DESCRIBE | DESC} tbl_name [col_name | wild]
An ellipsis (...) indicates the omission of a section of a statement,
typically to provide a shorter version of more complex syntax. For example,
INSERT ... SELECT is shorthand for the form of INSERT statement
that is followed by a SELECT statement.
An ellipsis can also indicate that the preceding syntax element of a statement may be repeated. In the following example, multiple reset_option values may be given, with each of those after the first preceded by commas:
RESET reset_option [,reset_option] ...
Commands for setting shell variables are shown using Bourne shell syntax. 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
If you are using csh or tcsh, you must issue commands somewhat
differently. You would execute the sequence just shown like this:
shell> setenv VARNAME value shell> some_command
MySQL, the most popular Open Source SQL database management system, is developed, distributed, and supported by MySQL AB. MySQL AB is a commercial company, founded by the MySQL developers. It is a second generation open source company that unites open source values and methodology with a successful business model. See section 1.3 Overview of MySQL AB.
The MySQL Web site (http://www.mysql.com/) provides the latest information about MySQL software and MySQL AB.
The official way to pronounce ``MySQL'' is ``My Ess Que Ell'' (not ``my sequel''), but we don't mind if you pronounce it as ``my sequel'' or in some other localized way.
We 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 or
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
designed to allow third-party code that was written for use with mSQL to
be ported easily for use with MySQL.
The derivation of the name MySQL is not clear. Our base directory and a large number of our libraries and tools have had the prefix ``my'' for well over 10 years. However, co-founder Monty Widenius's daughter is also named My. Which of the two gave its name to MySQL is still a mystery, even for us.
The name of the MySQL Dolphin (our logo) is ``Sakila,'' which was chosen by the founders of MySQL AB from a huge list of names suggested by users in our ``Name the Dolphin'' contest. The winning name was submitted by Ambrose Twebaze, an Open Source software developer from Swaziland, Africa. According to Ambrose, the name Sakila has its roots in SiSwati, the local language of Swaziland. Sakila is also the name of a town in Arusha, Tanzania, near Ambrose's country of origin, Uganda.
The following list describes some of the important characteristics of the MySQL Database Software. See also section 1.5 MySQL Development Roadmap for more information about current and upcoming features.
MyISAM) with index compression.
FLOAT, DOUBLE, CHAR, VARCHAR,
TEXT, BLOB, DATE, TIME, DATETIME,
TIMESTAMP, YEAR, SET, ENUM, and OpenGIS spatial
types.
See section 12 Column Types.
SELECT and WHERE
clauses of queries. For example:
mysql> SELECT CONCAT(first_name, ' ', last_name)
-> FROM citizen
-> WHERE income/dependents > 10000 AND age > 30;
GROUP BY and
ORDER BY clauses. Support
for group functions (COUNT(),
COUNT(DISTINCT ...),
AVG(), STD(),
SUM(), MAX(), MIN(), and GROUP_CONCAT()).
LEFT OUTER JOIN and RIGHT OUTER JOIN with both standard
SQL and ODBC syntax.
DELETE, INSERT, REPLACE, and UPDATE return
the number of rows that were changed (affected). It is possible to return
the number of rows matched instead by setting a flag when connecting to the
server.
SHOW command can be used to retrieve
information about databases, tables, and indexes. The EXPLAIN command
can be used to determine how the optimizer resolves a query.
ABS is a valid column name. The only restriction is that for a
function call, no spaces are allowed between the function name and the
`(' that follows it. See section 10.6 Treatment of Reserved Words in MySQL.
CHAR, VARCHAR,
BLOB, or TEXT column types.
latin1 (ISO-8859-1), german, big5, ujis,
and more. For example,
the Scandinavian characters `â', `ä' and `ö' are
allowed in table and column names.
Unicode support is available as of MySQL 4.1.
mysqlcheck client. MySQL also includes
myisamchk, a very fast command-line utility for performing these
operations on MyISAM tables.
See section 5 Database Administration.
--help or -?
options to obtain online assistance.
This section addresses the questions, ``How stable is MySQL Server?'' and, ``Can I depend on MySQL Server in this project?'' We will try to clarify these issues and answer some important questions that concern many potential users. The information in this section is based on data gathered from the mailing lists, which are very active in identifying problems as well as reporting types of use.
The original code stems back to the early 1980s. It provides a stable code
base, and the ISAM table format used by the original storage engine
remains backward-compatible.
At TcX, the predecessor of MySQL AB, MySQL code has worked
in projects since mid-1996, without any problems.
When the MySQL Database Software initially was released to a wider public,
our new users quickly found some pieces of untested code. Each new release
since then has had fewer portability problems, even though each new release
has also had many new features.
Each release of the MySQL Server has been usable. Problems have occurred only when users try code from the ``gray zones.'' Naturally, new users don't know what the gray zones are; this section therefore attempts to document those areas that are currently known. The descriptions mostly deal with Version 3.23, 4.0 and 4.1 of MySQL Server. All known and reported bugs are fixed in the latest version, with the exception of those listed in the bugs section, which are design-related. See section 1.8.7 Known Errors and Design Deficiencies in MySQL.
The MySQL Server design is multi-layered with independent modules. Some of the newer modules are listed here with an indication of how well-tested each of them is:
InnoDB tables (Stable)
InnoDB transactional storage engine has been declared
stable in the MySQL 3.23 tree, starting from version 3.23.49.
InnoDB is being used in large, heavy-load production systems.
BDB tables (Stable)
Berkeley DB code is very stable, but we are still improving
the BDB transactional storage engine interface in MySQL Server.
MyODBC 3.51 (Stable)
MyODBC 3.51 uses ODBC SDK 3.51 and is in wide production use.
Some issues brought up appear to be application-related and independent of
the ODBC driver or underlying database server.
MySQL 3.22 had a 4GB (4 gigabyte) limit on table size. With the
MyISAM storage engine in MySQL 3.23, the maximum table
size was increased to 8 million terabytes (2 ^ 63 bytes). With this larger
allowed table size, the maximum effective table size for MySQL
databases now usually is determined by operating system constraints
on file sizes, not by MySQL internal limits.
The InnoDB storage engine maintains InnoDB tables within a
tablespace that can be created from several files. This allows a
table to exceed the maximum individual file size. The tablespace can include
raw disk partitions, which allows extremely large tables. The maximum
tablespace size is 64TB.
The following table lists some examples of operating system file-size limits:
| Operating System | File-size Limit |
| Linux-Intel 32-bit | 2GB, much more when using LFS |
| Linux-Alpha | 8TB (?) |
| Solaris 2.5.1 | 2GB (4GB possible with patch) |
| Solaris 2.6 | 4GB (can be changed with flag) |
| Solaris 2.7 Intel | 4GB |
| Solaris 2.7 UltraSPARC | 512GB |
| NetWare w/NSS filesystem | 8TB |
On Linux 2.2, you can get MyISAM tables larger than 2GB in size by
using the Large File Support (LFS) patch for the ext2 filesystem. On Linux
2.4, patches also exist for ReiserFS to get support for big files. Most
current Linux distributions are based on kernel 2.4 and already include all
the required LFS patches. However, the maximum
available file size still depends on several factors, one of them being the
filesystem used to store MySQL tables.
For a detailed overview about LFS in Linux, have a look at Andreas Jaeger's Large File Support in Linux page at http://www.suse.de/~aj/linux_lfs.html.
By default, MySQL creates MyISAM tables with an internal
structure that allows a maximum size of about 4GB. You can
check the maximum table size for a table with the SHOW TABLE STATUS
statement or with myisamchk -dv tbl_name.
See section 14.5.3 SET and SHOW Syntax.
If you need a MyISAM table that will be larger than 4GB in size (and your
operating system supports large files), the CREATE TABLE statement
allows AVG_ROW_LENGTH and MAX_ROWS options.
See section 14.2.6 CREATE TABLE Syntax.
You can also change these options with ALTER TABLE after the table has
been created, to increase the table's maximum allowable size.
See section 14.2.2 ALTER TABLE Syntax.
Other ways to work around file-size limits for MyISAM tables are as
follows:
myisampack to
compress it. myisampack usually compresses a table by at
least 50%, so you can have, in effect, much bigger tables.
myisampack also can merge multiple tables into a single table.
See section 8.2 myisampack, the MySQL Compressed Read-only Table Generator.
MyISAM
data files is by using the RAID options.
See section 14.2.6 CREATE TABLE Syntax.
MERGE library that allows
you to handle a collection of MyISAM tables that have identical
structure as a single MERGE table.
See section 15.2 The MERGE Storage Engine.
The MySQL Server itself has no problems with Year 2000 (Y2K) compliance:
2037 for TIMESTAMP values. For DATE and DATETIME
values, dates through the year 9999 are accepted.
YEAR column type
can store years 0 and 1901 to 2155 in one byte and
display them using two or four digits.
All two-digit years are considered to be in the range
1970 to 2069, which means that if you store 01 in a
YEAR column, MySQL Server treats it as 2001.
The following simple demonstration illustrates that MySQL Server
has no problems with DATE or DATETIME values through the year
9999, and no problems with TIMESTAMP values until after 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 (0.01 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),
-> ('2040-01-01','2040-01-01 00:00:00',20400101000000),
-> ('9999-12-31','9999-12-31 23:59:59',99991231235959);
Query OK, 14 rows affected (0.01 sec)
Records: 14 Duplicates: 0 Warnings: 2
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 |
| 2040-01-01 | 2040-01-01 00:00:00 | 00000000000000 |
| 9999-12-31 | 9999-12-31 23:59:59 | 00000000000000 |
+------------+---------------------+----------------+
14 rows in set (0.00 sec)
The final two TIMESTAMP column values are zero because the
year values (2040, 9999) exceed the TIMESTAMP maximum. The
TIMESTAMP data type, which is used to store the current time,
supports values that range from 19700101000000 to
20300101000000 on 32-bit machines (signed value). On 64-bit
machines, TIMESTAMP handles values up to 2106 (unsigned
value).
Although MySQL Server itself is Y2K-safe, you may run into
problems if you use it with applications that are not Y2K-safe.
For example, many old applications store or manipulate years using
two-digit values (which are ambiguous) rather than four-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.
Thus, even though MySQL Server has no Y2K problems, it is the application's responsibility to provide unambiguous input. See section 12.3.4 Y2K Issues and Date Types for MySQL Server's rules for dealing with ambiguous date input data that contains two-digit year values.
MySQL AB is the company of the MySQL founders and main developers. MySQL AB was originally established in Sweden by David Axmark, Allan Larsson, and Michael ``Monty'' Widenius.
The developers of the MySQL server are all employed by the company. We are a virtual organization with people in a dozen countries around the world. We communicate extensively over the Internet every day with one another and with our users, supporters, and partners.
We are dedicated to developing the MySQL database software and promoting it to new users. MySQL AB owns the copyright to the MySQL source code, the MySQL logo and (registered) trademark, and this manual. See section 1.2 Overview of the MySQL Database Management System.
The MySQL core values show our dedication to MySQL and Open Source.
These core values direct how MySQL AB works with the MySQL server software:
These are the core values of the company MySQL AB and its employees:
The MySQL Web site (http://www.mysql.com/) provides the latest information about MySQL and MySQL AB.
By the way, the ``AB'' part of the company name is the acronym for the Swedish ``aktiebolag,'' or ``stock company.'' It translates to ``MySQL, Inc.'' In fact, MySQL, Inc. and MySQL GmbH are examples of MySQL AB subsidiaries. They are located in the US and Germany, respectively.
One of the most common questions we encounter is, ``How can you make a living from something you give away for free?'' This is how:
The company has been profitable since its inception. In October 2001, we accepted venture financing from leading Scandinavian investors and a handful of business angels. This investment is used to solidify our business model and build a basis for sustainable growth.
MySQL AB is run and owned by the founders and main developers of the MySQL database. The developers are committed to providing support to customers and other users in order to stay in touch with their needs and problems. All our support is provided by qualified developers. Really tricky questions are answered by Michael ``Monty'' Widenius, principal author of the MySQL Server.
Paying customers receive high-quality support directly from MySQL AB. MySQL AB also provides the MySQL mailing lists as a community resource where anyone may ask questions.
For more information and ordering support at various levels, see section 1.4 MySQL Support and Licensing.
MySQL AB delivers MySQL and related training worldwide. We offer both open courses and in-house courses tailored to the specific needs of your company. MySQL Training is also available through our partners, the Authorized MySQL Training Centers.
Our training material uses the same sample databases used in our documentation and our sample applications, and is always updated to reflect the latest MySQL version. Our trainers are backed by the development team to guarantee the quality of the training and the continuous development of the course material. This also ensures that no questions raised during the courses remain unanswered.
Attending our training courses will enable you to achieve your MySQL application goals. You will also:
If you are interested in our training as a potential participant or as a training partner, please visit the training section at http://www.mysql.com/training/, or send email to training@mysql.com.
For details about the MySQL Certification Program, please see http://www.mysql.com/certification/.
MySQL AB and its Authorized Partners offer consulting services to users of MySQL Server and to those who embed MySQL Server in their own software, all over the world.
Our consultants can help you design and tune your databases, construct efficient queries, tune your platform for optimal performance, resolve migration issues, set up replication, build robust transactional applications, and more. We also help customers embed MySQL Server in their products and applications for large-scale deployment.
Our consultants work in close collaboration with our development team, which ensures the technical quality of our professional services. Consulting assignments range from two-day power-start sessions to projects that span weeks and months. Our expertise covers not only MySQL Server, it also extends into programming and scripting languages such as PHP, Perl, and more.
If you are interested in our consulting services or want to become a consulting partner, please visit the consulting section of our Web site at http://www.mysql.com/consulting/ or contact our consulting staff at consulting@mysql.com.
The MySQL database is released under the GNU General Public License (GPL). This means that the MySQL software can be used free of charge under the GPL. If you do not want to be bound by the GPL terms (such as the requirement that your application must also be GPL), you may purchase a commercial license for the same product from MySQL AB; see https://order.mysql.com/. Since MySQL AB owns the copyright to the MySQL source code, we are able to employ Dual Licensing, which means that the same product is available under GPL and under a commercial license. This does not in any way affect the Open Source commitment of MySQL AB. For details about when a commercial license is required, please see section 1.4.3 MySQL Licenses.
We also sell commercial licenses of third-party Open Source GPL
software that adds value to MySQL Server. A good example is the
InnoDB transactional storage engine that offers ACID
support, row-level locking, crash recovery, multi-versioning, foreign
key support, and more. See section 16 The InnoDB Storage Engine.
MySQL AB has a worldwide partner program that covers training courses, consulting and support, publications, plus reselling and distributing MySQL and related products. MySQL AB Partners get visibility on the http://www.mysql.com/ Web site and the right to use special versions of the MySQL (registered) trademarks to identify their products and promote their business.
If you are interested in becoming a MySQL AB Partner, please email partner@mysql.com.
The word MySQL and the MySQL dolphin logo are (registered) trademarks of MySQL AB. See section 1.4.4 MySQL AB Logos and Trademarks. These trademarks represent a significant value that the MySQL founders have built over the years.
The MySQL Web site (http://www.mysql.com/) is popular among developers and users. In December 2003, we served 16 million page views. Our visitors represent a group that makes purchase decisions and recommendations for both software and hardware. Twelve percent of our visitors authorize purchase decisions, and only nine percent have no involvement at all in purchase decisions. More than 65% have made one or more online business purchases within the last half-year, and 70% plan to make one in the next few months.
The MySQL Web site (http://www.mysql.com/) provides the latest information about MySQL and MySQL AB.
For press services and inquiries not covered in our news releases (http://www.mysql.com/news-and-events/), please send email to press@mysql.com.
If you have a support contract with MySQL AB, you will get timely, precise answers to your technical questions about the MySQL software. For more information, see section 1.4.1 Support Offered by MySQL AB. On our Web site, see http://www.mysql.com/support/, or send email to sales@mysql.com.
For information about MySQL training, please visit the training section at http://www.mysql.com/training/, or send email to training@mysql.com. See section 1.3.1.2 Training and Certification.
For information on the MySQL Certification Program, please see http://www.mysql.com/certification/. See section 1.3.1.2 Training and Certification.
If you're interested in consulting, please visit the consulting section of our Web site at http://www.mysql.com/consulting/, or send email to consulting@mysql.com. See section 1.3.1.3 Consulting.
Commercial licenses may be purchased online at https://order.mysql.com/. There you will also find information on how to fax your purchase order to MySQL AB. More information about licensing can be found at http://www.mysql.com/products/licensing/. If you have questions regarding licensing or you want a quote for high-volume licensing, please fill in the contact form on our Web site (http://www.mysql.com/), or send email to licensing@mysql.com (for licensing questions) or to sales@mysql.com (for sales inquiries). See section 1.4.3 MySQL Licenses.
If you represent a business that is interested in partnering with MySQL AB, please send email to partner@mysql.com. See section 1.3.1.5 Partnering.
For more information on the MySQL trademark policy, refer to http://www.mysql.com/company/trademark.html, or send email to trademark@mysql.com. See section 1.4.4 MySQL AB Logos and Trademarks.
If you are interested in any of the MySQL AB jobs listed in our jobs section (http://www.mysql.com/company/jobs/), please send email to jobs@mysql.com. Please do not send your CV as an attachment, but rather as plain text at the end of your email message.
For general discussion among our many users, please direct your attention to the appropriate mailing list. See section 1.7.1 MySQL Mailing Lists.
Reports of errors (often called ``bugs''), as well as questions and comments, should be sent to the general MySQL mailing list. See section 1.7.1.1 The MySQL Mailing Lists. If you have found a sensitive security bug in MySQL Server, please let us know immediately by sending email to security@mysql.com. See section 1.7.1.3 How to Report Bugs or Problems.
If you have benchmark results that we can publish, please contact us via email at benchmarks@mysql.com.
If you have suggestions concerning additions or corrections to this manual, please send them to the documentation team via email at docs@mysql.com.
For questions or comments about the workings or content of the MySQL Web site (http://www.mysql.com/), please send email to webmaster@mysql.com.
MySQL AB has a privacy policy, which can be read at http://www.mysql.com/company/privacy.html. For any queries regarding this policy, please send email to privacy@mysql.com.
For all other inquiries, please send email to info@mysql.com.
This section describes MySQL support and licensing arrangements.
Technical support from MySQL AB means individualized answers to your unique problems direct from the software engineers who code the MySQL database engine.
We try to take a broad and inclusive view of technical support. Almost any problem involving MySQL software is important to us if it's important to you. Typically customers seek help on how to get different commands and utilities to work, remove performance bottlenecks, restore crashed systems, understand the impact of operating system or networking issues on MySQL, set up best practices for backup and recovery, utilize APIs, and so on. Our support covers only the MySQL server and our own utilities, not third-party products that access the MySQL server, although we try to help with these where we can.
Detailed information about our various support options is given at http://www.mysql.com/support/, where support contracts can also be ordered online. To contact our sales staff, send email to sales@mysql.com.
Technical support is like life insurance. You can live happily without it for years. However, when your hour arrives, it becomes critically important, but it's too late to buy it. If you use MySQL Server for important applications and encounter sudden difficulties, it may be too time-consuming to figure out all the answers yourself. You may need immediate access to the most experienced MySQL troubleshooters available, those employed by MySQL AB.
MySQL AB owns the copyright to the MySQL source code, the MySQL logos and (registered) trademarks, and this manual. See section 1.3 Overview of MySQL AB. Several different licenses are relevant to the MySQL distribution:
mysqlclient
library and the client, as well as the GNU readline library,
are covered by the GNU General Public License.
See section G GNU General Public License.
The text of this license can be found as the file `COPYING'
in MySQL distributions.
getopt library is covered by the
GNU Lesser General Public License.
See http://www.fsf.org/licenses/.
regexp library) are covered
by a Berkeley-style copyright.
For information about how the MySQL licenses work in practice, please refer to section 1.4.3 MySQL Licenses and section 1.4.4 MySQL AB Logos and Trademarks.
The MySQL software is released under the GNU General Public License (GPL), which is probably the best known Open Source license. The formal terms of the GPL license can be found at http://www.fsf.org/licenses/. See also http://www.fsf.org/licenses/gpl-faq.html and http://www.gnu.org/philosophy/enforcing-gpl.html.
Our GPL licensing is supported by an optional license exception that enables many Free/Libre and Open Source Software (``FLOSS'') applications to include the GPL-licensed MySQL client libraries despite the fact that not all FLOSS licenses are compatible with the GPL. For details, see http://www.mysql.com/products/licensing/foss-exception.html.
Because the MySQL software is released under the GPL, it may often be used for free, but for certain uses you may want or need to buy commercial licenses from MySQL AB at https://order.mysql.com/. See http://www.mysql.com/products/licensing/ for more information.
Older versions of MySQL (3.22 and earlier) are subject to a stricter license (http://www.mysql.com/products/licensing/mypl.html). See the documentation of the specific version for information.
Please note that the use of the MySQL software under commercial license, GPL, or the old MySQL license does not automatically give you the right to use MySQL AB (registered) trademarks. See section 1.4.4 MySQL AB Logos and Trademarks.
The GPL license is contagious in the sense that when a program is linked to a GPL program, all the source code for all the parts of the resulting product must also be released under the GPL. If you do not follow this GPL requirement, you break the license terms and forfeit your right to use the GPL program altogether. You also risk damages.
You need a commercial license under these conditions:
Our GPL licensing is supported by an optional license exception that enables many Free/Libre and Open Source Software (``FLOSS'') applications to include the GPL-licensed MySQL client libraries despite the fact that not all FLOSS licenses are compatible with the GPL. For details, see http://www.mysql.com/products/licensing/foss-exception.html.
If you require a commercial license, you will need one for each installation of the MySQL software. This covers any number of CPUs on a machine, and there is no artificial limit on the number of clients that connect to the server in any way.
For commercial licenses, please visit our Web site at http://www.mysql.com/products/licensing/. For support contracts, see http://www.mysql.com/support/. If you have special needs, please contact our sales staff via email at sales@mysql.com.
You can use the MySQL software for free under the GPL if you adhere to the conditions of the GPL. For additional details about the GPL, including answers to common questions, see the generic FAQ from the Free Software Foundation at http://www.fsf.org/licenses/gpl-faq.html.
Our GPL licensing is supported by an optional license exception that enables many Free/Libre and Open Source Software (``FLOSS'') applications to include the GPL-licensed MySQL client libraries despite the fact that not all FLOSS licenses are compatible with the GPL. For details, see http://www.mysql.com/products/licensing/foss-exception.html.
Common uses of the GPL include:
If your use of MySQL database software does not require a commercial license, we encourage you to purchase support from MySQL AB anyway. This way you contribute toward MySQL development and also gain immediate advantages for yourself. See section 1.4.1 Support Offered by MySQL AB.
If you use the MySQL database software in a commercial context such that you profit by its use, we ask that you further the development of the MySQL software by purchasing some level of support. We feel that if the MySQL database helps your business, it is reasonable to ask that you help MySQL AB. (Otherwise, if you ask us support questions, you are not only using for free something into which we've put a lot a work, you're asking us to provide free support, too.)
Many users of the MySQL database want to display the MySQL AB dolphin logo on their Web sites, books, or boxed products. We welcome and encourage this, although it should be noted that the word MySQL and the MySQL dolphin logo are (registered) trademarks of MySQL AB and may only be used as stated in our trademark policy at http://www.mysql.com/company/trademark.html.
The MySQL dolphin logo was designed by the Finnish advertising agency Priority in 2001. The dolphin was chosen as a suitable symbol for the MySQL database management system, which is like a smart, fast, and lean animal, effortlessly navigating oceans of data. We also happen to like dolphins.
The original MySQL logo may only be used by representatives of MySQL AB and by those having a written agreement allowing them to do so.
We have designed a set of special Conditional Use logos that may be downloaded from our Web site at http://www.mysql.com/press/logos.html and used on third-party Web sites without written permission from MySQL AB. The use of these logos is not entirely unrestricted but, as the name implies, subject to our trademark policy that is also available on our Web site. You should read through the trademark policy if you plan to use them. The requirements are basically as follows:
Contact us via email at trademark@mysql.com to inquire about special arrangements to fit your needs.
You need written permission from MySQL AB before using MySQL logos in the following cases:
Due to legal and commercial reasons, we monitor the use of MySQL (registered) trademarks on products, books, and other items. We usually require a fee for displaying MySQL AB logos on commercial products, since we think it is reasonable that some of the revenue is returned to fund further development of the MySQL database.
MySQL partnership logos may be used only by companies and persons having a written partnership agreement with MySQL AB. Partnerships include certification as a MySQL trainer or consultant. For more information, please see section 1.3.1.5 Partnering.
MySQL AB welcomes references to the MySQL database, but it should be
noted that the word MySQL is a registered trademark of MySQL AB.
Because of this, you must append the ``registered trademark'' notice
symbol (R) to
the first or most prominent use of the word MySQL in a text and,
where appropriate, state that MySQL is a registered trademark of
MySQL AB. For more information, please refer to our trademark policy at
http://www.mysql.com/company/trademark.html.
Use of the word MySQL in company or product names or in Internet domain names is not allowed without written permission from MySQL AB. http://www.mysql.com/company/contact/.
This section provides a snapshot of the MySQL development roadmap, including major features implemented or planned for MySQL 4.0, 4.1, 5.0, and 5.1. The following sections provide information for each release series.
The current production release series is MySQL 4.1, which was declared stable for production use as of Version 4.1.7, released in October 2004. The previous production release series is MySQL 4.0, which was declared stable for production use as of Version 4.0.12, released in March 2003. Production status means that future 4.1 and 4.0 development is limited only to bugfixes. For the older MySQL 3.23 series, only critical bugfixes are made.
Active MySQL development currently is taking place in the MySQL 5.0 release series, this means that new features are being added there. MySQL 5.0 is available in alpha status.
Before upgrading from one release series to the next, please see the notes at section 2.10 Upgrading/Downgrading MySQL.
Plans for some of the most requested features are summarized in the following table.
| Feature | MySQL Series |
| Unions | 4.0 |
| Subqueries | 4.1 |
| R-trees | 4.1 (for MyISAM tables)
|
| Stored procedures | 5.0 |
| Views | 5.0 |
| Cursors | 5.0 |
| Foreign keys | 5.1 (already implemented in 3.23 for InnoDB)
|
| Triggers | 5.0 and 5.1 |
| Full outer join | 5.1 |
| Constraints | 5.1 |
MySQL Server 4.0 is available in production status.
MySQL 4.0 is available for download at http://dev.mysql.com/ and from our mirrors. MySQL 4.0 has been tested by a large number of users and is in production use at many large sites.
The major new features of MySQL Server 4.0 are geared toward our existing business and community users, enhancing the MySQL database software as the solution for mission-critical, heavy-load database systems. Other new features target the users of embedded databases.
INSERT statements, searching on
packed indexes, full-text searching (using FULLTEXT indexes), and
COUNT(DISTINCT).
InnoDB storage engine as standard
InnoDB storage engine is offered as a standard feature of the
MySQL server. This means full support for ACID transactions, foreign
keys with cascading UPDATE and DELETE, and row-level locking
are now standard features.
See section 16 The InnoDB Storage Engine.
FULLTEXT search properties of MySQL Server 4.0 enables
FULLTEXT indexing of large text masses with both binary
and natural-language searching logic. You can customize minimal word
length and define your own stop word lists in any human language,
enabling a new set of applications to be built with MySQL Server.
See section 13.6 Full-Text Search Functions.
UNION statement, a long-awaited standard SQL feature.
TRUNCATE TABLE (as in Oracle).
latin1_de, which ensures that the
German sorting order sorts words with umlauts in the same order
as do German telephone books.
mysqld parameters (startup options) can be set without taking
down the server. This is a convenient feature for database administrators
(DBAs).
See section 14.5.3.1 SET Syntax.
DELETE and UPDATE statements have been added.
MyISAM storage engine supports symbolic
linking at the table level (and not just the database level as before).
SQL_CALC_FOUND_ROWS and FOUND_ROWS() are new functions that make it
possible to find out the number of rows a SELECT query that includes a
LIMIT clause would have returned without that clause.
The news section of this manual includes a more in-depth list of features. See section C.3 Changes in release 4.0.x (Production).
The libmysqld embedded server library makes MySQL Server suitable for
a vastly expanded realm of applications. By using this library, developers can
embed MySQL Server into various applications and electronics devices, where
the end user has no knowledge of there actually being an underlying
database. Embedded MySQL Server is ideal for use behind
the scenes in Internet appliances, public kiosks, turnkey
hardware/software combination units, high performance Internet
servers, self-contained databases distributed on CD-ROM, and so on.
Many users of libmysqld will benefit from the MySQL
Dual Licensing. For those not wishing to be bound by the GPL,
the software is also made available under a commercial license.
The embedded MySQL library uses the same interface as the normal
client library, so it is convenient and easy to use.
See section 21.2.16 libmysqld, the Embedded MySQL Server Library.
On windows there are two different libraries:
libmysqld.lib | Dynamic library for threaded applications. |
mysqldemb.lib | Static library for not threaded applications. |
MySQL Server 4.0 laid the foundation for new features implemented in MySQL 4.1, such as subqueries and Unicode support, and for the work on stored procedures being done in version 5.0. These features come at the top of the wish list of many of our customers. Already well-known for its stability, speed, and ease of use, MySQL Server is now able to fulfill the requirement checklists of very demanding buyers.
MySQL Server 4.1 is currently in production status, and binaries are available for download at http://dev.mysql.com/downloads/mysql/4.1.html. All binary releases pass our extensive test suite without any errors on the platforms on which we test. See section C.2 Changes in release 4.1.x (Production).
For those wishing to use the most recent development source for MySQL 4.1, we also make our BitKeeper repositories publicly available. See section 2.8.3 Installing from the Development Source Tree.
This section lists features implemented in MySQL 4.1. New features that will be available in MySQL 5.0 are described in section 1.6.1 New Features Planned for 5.0.
SELECT statement nested within another statement.
A ``derived table'' (an unnamed view) is a subquery in the FROM clause
of another statement.
See section 14.1.8 Subquery Syntax.
BTREE indexing is supported for HEAP tables,
significantly improving response time for non-exact searches.
CREATE TABLE tbl_name2 LIKE tbl_name1 allows you to create, with
a single statement, a new table with a structure exactly like that of an
existing table.
MyISAM storage engine supports
OpenGIS spatial types for storing geographical data.
See section 19 Spatial Extensions in MySQL.
SHOW WARNINGS shows warnings for the last command.
See section 14.5.3.21 SHOW WARNINGS Syntax.
utf8 and ucs2 character sets.
HELP command that can be used
to get help information for SQL statements.
The advantage of having this information on the server side is that the
information is always applicable to the particular server version that you
actually are using.
Because this information is available by issuing an SQL statement, any client
can be written to access it.
For example, the help command of the mysql command-line client
has been modified to have this capability.
INSERT ... ON DUPLICATE KEY UPDATE ... syntax has been
implemented. This allows you to UPDATE an existing row if the
INSERT would have caused a duplicate in a PRIMARY or
UNIQUE index.
See section 14.1.4 INSERT Syntax.
GROUP_CONCAT()
adds the extremely useful capability of concatenating column values from
grouped rows into a single result string.
See section 13.9 Functions and Modifiers for Use with GROUP BY Clauses.
The news section of this manual includes a more in-depth list of features. See section C.2 Changes in release 4.1.x (Production).
New development for MySQL is focused on the 5.0 release, featuring stored procedures, updatable views, rudimentary triggers, and other new features. See section 1.6.1 New Features Planned for 5.0.
For those wishing to take a look at the bleeding edge of MySQL development, we make our BitKeeper repository for MySQL version 5.0 publicly available. See section 2.8.3 Installing from the Development Source Tree. As of December 2003, binary builds of version 5.0 have also been available.
This section summarizes the features that we plan to implement in MySQL Server. The items are ordered by release series. Within a list, items are shown in approximately the order they will be done.
Note: If you are an enterprise-level user with an urgent need for a particular feature, please contact sales@mysql.com to discuss sponsoring options. Targeted financing by sponsor companies allows us to allocate additional resources for specific purposes. One example of a feature sponsored in the past is replication.
The following features are planned for inclusion into MySQL 5.0. Some of the features such as stored procedures are complete and are included in MySQL 5.0 alpha, which is available now. Others such as cursors are only partially available. Expect these and other features to mature and be fully supported in upcoming releases.
Note that because we have many developers that are working on different projects, there will also be many additional features. There is also a small chance that some of these features will be added to MySQL 4.1. For a list what is already done in MySQL 4.1, see section 1.5.2.1 Features Available in MySQL 4.1.
For those wishing to take a look at the bleeding edge of MySQL development, we make our BitKeeper repository for MySQL version 5.0 publicly available. See section 2.8.3 Installing from the Development Source Tree. As of December 2003, binary builds of version 5.0 are also available.
CREATE VIEW Syntax.
MyISAM tables that an index
should be created as an RTREE index. (In MySQL 4.1, RTREE indexes
are used internally for geometrical data that use GIS data types, but cannot be
created on request.)
MEMORY tables.
INFORMATION_SCHEMA.
VARCHAR support (column lengths longer than 255, and
no stripping of trailing whitespace).
There is already support for this in the MyISAM storage engine,
but it is not yet available at the user level.
SHOW COLUMNS FROM tbl_name (used by the mysql client to allow
expansions of column names) should not open the table, only the
definition file. This will require less memory and be much faster.
DELETE on MyISAM tables to use the record cache.
To do this, we need to update the threads record cache when we update
the `.MYD' file.
MEMORY tables:
RENAME TABLE on a table used in an active
MERGE table possibly corrupting the table.
The news section of this manual includes a more in-depth list of features. See section C.1 Changes in release 5.0.x (Development).
FOREIGN KEY support for all table types, not just InnoDB.
BIT type to take one bit. (BIT now takes one byte;
it is treated as a synonym for TINYINT.)
RENAME DATABASE. To make this safe for all storage engines,
it should work as follows:
RENAME command.
CONNECT BY PRIOR to search tree-like (hierarchical)
structures.
SUM(DISTINCT).
INSERT SQL_CONCURRENT and mysqld --concurrent-insert to do
a concurrent insert at the end of a table if the table is read-locked.
UPDATE statements. For example:
UPDATE foo SET @a:=a+b,a=@a, b=@a+c.
GROUP BY, as in the following statement:
SELECT id, @a:=COUNT(*), SUM(sum_col)/@a FROM tbl_name GROUP BY id.
IMAGE option to LOAD DATA INFILE to not update
TIMESTAMP and AUTO_INCREMENT columns.
LOAD DATA INFILE ... UPDATE syntax that works like this:
LOAD DATA INFILE ... REPLACE INTO.
LOAD DATA INFILE understand syntax like this:
LOAD DATA INFILE 'file_name.txt' INTO TABLE tbl_name
TEXT_FIELDS (text_col1, text_col2, text_col3)
SET table_col1=CONCAT(text_col1, text_col2),
table_col3=23
IGNORE text_col3
This can be used to skip over extra columns in the text file,
or update columns based on expressions of the read data.
SET type columns:
ADD_TO_SET(value,set)
REMOVE_FROM_SET(value,set)
mysql in the middle of a query, you should open
another connection and kill the old running query.
Alternatively, an attempt should be made to detect this in the server.
SHOW INFO FROM tbl_name for basic table information
should be implemented.
SELECT a FROM tbl_name1 LEFT JOIN tbl_name2 USING (a); in this
case a is assumed to come from tbl_name1.
DELETE and REPLACE options to the UPDATE statement
(this will delete rows when a duplicate-key error occurs while updating).
DATETIME to store fractions of seconds.
regexp library instead of the current
one (the new library should be much faster than the current one).
ANY(), EVERY(), and SOME() group functions. In
standard SQL, these work only on boolean columns, but we can extend these to
work on any columns or expressions by treating a value of zero as FALSE and
non-zero values as TRUE.
MAX(column) to be the same as the column type:
mysql> CREATE TABLE t1 (a DATE); mysql> INSERT INTO t1 VALUES (NOW()); mysql> CREATE TABLE t2 SELECT MAX(a) FROM t1; mysql> SHOW COLUMNS FROM t2;
MyISAM
recovery at the same time.
INSERT INTO ... SELECT to optionally use concurrent inserts.
SELECT MIN(column) ... GROUP BY.
long_query_time with a granularity
in microseconds.
myisampack code into the server so that it can perform
PACK or COMPRESS operations.
INSERT/DELETE/UPDATE so that we
can gracefully recover if the index file gets full.
ALTER TABLE on a table that is symlinked to another
disk, create temporary tables on that disk.
DATE/DATETIME type that handles time zone information
properly, to make dealing with dates in different time zones easier.
configure so that all libraries (like MyISAM)
can be compiled without threads.
LIMIT arguments; for example,
LIMIT @a,@b.
mysql to a Web browser.
LOCK DATABASES (with various options).
SHOW STATUS. Record reads and
updates. Selects on a single table and selects with joins. Mean number of
tables in selects. Number of ORDER BY and GROUP BY queries.
mysqladmin copy database new-database; this requires a COPY
operation to be added to mysqld.
SHOW HOSTS for printing information about the hostname cache.
NULL for calculated columns.
Item_copy_string on numerical values to avoid
number-to-string-to-number conversion in case of
SELECT COUNT(*)*(id+0) FROM tbl_name GROUP BY id.
ALTER TABLE doesn't abort clients
that execute INSERT DELAYED.
UPDATE clause,
they contain the old values from before the update started.
get_changed_tables(timeout,table1,table2,...).
mmap() when possible. Now only
compressed tables use mmap().
SET TIMESTAMP=val;.
n, replace other
occurrences of col_name within the expression with n.
Currently, this is done only for some simple cases.
MINUS, INTERSECT, and FULL OUTER JOIN.
(Currently UNION and LEFT|RIGHT OUTER JOIN are supported.)
SQL_OPTION MAX_SELECT_TIME=val, for placing a time limit on a query.
LIMIT to allow retrieval of data from the end of a result set.
mysqld_safe: According to FSSTND (which
Debian tries to follow), PID files should go into `/var/run/<progname>.pid'
and log files into `/var/log'. It would be nice if you could put the
"DATADIR" in the first declaration of "pidfile" and "log" so that the
placement of these files can be changed with a single statement.
LOAD DATA INFILE statement
to read files that have been compressed with gzip.
BLOB columns (partly solved now).
JOIN with parentheses.
GET_LOCK() to obtain more than one lock. When doing this, it is
also necessary to handle the possible deadlocks this change will introduce.
We aim toward full compliance with ANSI/ISO SQL. There are no features we plan not to implement.
This section introduces the MySQL mailing lists and provides guidelines as to how the lists should be used. When you subscribe to a mailing list, you will receive all postings to the list as email messages. You can also send your own questions and answers to the list.
To subscribe to or unsubscribe from any of the mailing lists described in this section, visit http://lists.mysql.com/. For most of them, you can select the regular version of the list where you get individual messages, or a digest version where you get one large message per day.
Please do not send messages about subscribing or unsubscribing to any of the mailing lists, because such messages are distributed automatically to thousands of other users.
Your local site may have many subscribers to a MySQL mailing list.
If so, the site 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 MySQL mailing lists are as follows:
announce
mysql
bugs
internals
mysqldoc
benchmarks
packagers
java
win32
myodbc
gui-tools
MySQL
Administrator and the MySQL Control Center graphical client.
cluster
dotnet
plusplus
perl
DBD::mysql.
If you're unable to get an answer to your questions from a MySQL mailing list, one option is to purchase support from MySQL AB. This will put you in direct contact with MySQL developers. See section 1.4.1 Support Offered by MySQL AB.
The following table shows some MySQL mailing lists in languages other than English. These lists are not operated by MySQL AB.
mysql-france-subscribe@yahoogroups.com
list@tinc.net
subscribe mysql your@email.address to this list.
mysql-de-request@lists.4t2.com
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
subscribe mysql-br your@email.address to this list.
mysql-alta@elistas.net
subscribe mysql your@email.address to this list.
Before posting a bug report or question, please do the following:
If you can't find an answer in the manual or the archives, check with your local MySQL expert. If you still can't find an answer to your question, please follow the guidelines on sending mail to a MySQL mailing list, outlined in the next section, before contacting us.
The normal place to report bugs is http://bugs.mysql.com/, which is the address for our bugs database. This database is public, and can be browsed and searched by anyone. If you log in to the system, you will also be able to enter new reports.
Writing a good bug report takes patience, but doing it right the first time saves time both for us and for yourself. A good bug report, containing a full test case for the bug, makes it very likely that we will fix the bug 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). mysqlbug can be
found in the `scripts' directory (source distribution) and in the
`bin' directory under your MySQL installation directory (binary distribution).
If you are unable to use mysqlbug (for example, if you are running
on Windows), it is still vital that you include all the necessary information
noted in this section (most importantly, a description of the operating system
and the MySQL version).
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.
Preferably, you should test the problem using the latest production or
development version of MySQL Server before posting. Anyone should be
able to repeat the bug by just using mysql test < script_file on the
included test case or by running the shell or Perl script that is included in the
bug report.
All bugs posted in the bugs database at http://bugs.mysql.com/ will be corrected or documented in the next MySQL release. If only minor code changes are needed to correct a problem, we may also post a patch that fixes the problem.
If you have found a sensitive security bug in MySQL, you can send email to security@mysql.com.
If you have a repeatable bug report, please report it to the bugs
database at http://bugs.mysql.com/. Note that even in this case
it's good to run the mysqlbug script first to find information
about your system. Any bug that we are able to repeat has a high chance
of being fixed in the next MySQL release.
To report other problems, you can use one of the MySQL mailing lists.
Remember that it is possible for us to respond to a message containing too much information, but not to one containing too little. People often omit facts because they think they know the cause of a problem and assume that some details don't matter. A good principle is this: If you are in doubt about stating something, state it. It is faster and less troublesome to write a couple more lines in your report than to wait longer for the answer if we must ask you to provide information that was missing from the initial report.
The most common errors made in bug reports are (a) not including the version number of the MySQL distribution used, and (b) not fully describing the platform on which the MySQL server is installed (including the platform type and 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 already been fixed in newer MySQL versions. Sometimes the error is platform-dependent; in such cases, it is next to impossible for us to fix anything without knowing the operating system and the version number of the platform.
If you compiled MySQL from source, remember also to provide information about your compiler, if it is related to the problem. Often people find bugs in compilers and think the problem is MySQL-related. Most compilers are under development all the time and become better version by version. To determine whether your problem depends on your compiler, we need to know what compiler you use. Note that every compiling problem should be regarded as a bug and reported accordingly.
It is most helpful when a good description of the problem is included in the bug report. That is, give a good example of everything you did that led to the problem and describe, in exact detail, the problem itself. The best reports are those that include a full example showing how to reproduce the bug or problem. See section D.1.6 Making a Test Case If 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 lettercase should be observed.) You should never try to reproduce from memory what the error message was; instead, copy and paste the entire message into your report.
If you have a problem with Connector/ODBC (MyODBC), please try to generate a trace file and send it with your report. See section 22.1.1.9 How to Report MyODBC Problems or Bugs.
Please remember that many of the people who will read your report will
do so using an 80-column display. When generating reports or examples
using the mysql command-line tool, you should therefore use
the --vertical option (or the \G statement terminator)
for output that would exceed the available width for such a display
(for example, with the EXPLAIN SELECT statement; see the
example later in this section).
Please include the following information in your report:
mysqladmin version. The mysqladmin
program can be found in the `bin' directory under your MySQL
installation directory.
uname -a.
mysqld died, you should also report the query that crashed
mysqld. You can usually find this out by running mysqld with
query logging enabled, and then looking in the log after mysqld crashes
See section D.1.5 Using Log Files to Find Cause of Errors in mysqld.
mysqldump --no-data db_name tbl_name. This is very easy
to do and is a powerful way to get information about any table in a database.
The information will help us create a situation matching the one you have.
SELECT statements, you
should always include the output of EXPLAIN SELECT ..., and at
least the number of rows that the SELECT statement produces. You
should also include the output from SHOW CREATE TABLE tbl_name
for each involved table. The more information you give about your
situation, the more likely it is that someone can help you.
The following is an example of a very good bug report. It should be posted
with the mysqlbug script. The example uses the mysql
command-line tool. Note the use of the \G statement terminator for
statements whose output width would otherwise exceed that of an 80-column
display device.
mysql> SHOW VARIABLES;
mysql> SHOW COLUMNS FROM ...\G
<output from SHOW COLUMNS>
mysql> EXPLAIN SELECT ...\G
<output from EXPLAIN>
mysql> FLUSH STATUS;
mysql> SELECT ...;
<A short version of the output from SELECT,
including the time taken to run the query>
mysql> SHOW STATUS;
<output from SHOW STATUS>
mysqld, try to provide an
input script that will reproduce the anomaly. This script should include any
necessary source files. The more closely the script can reproduce your
situation, the better. If you can make a reproducible test case, you should
post it on http://bugs.mysql.com/ for high-priority treatment.
If you can't provide a script, you should at least include the output
from mysqladmin variables extended-status processlist in your mail to
provide some information on how your system is performing.
mysqldump and create a `README' file
that describes your problem.
Create a compressed archive of your files using
tar and gzip or zip, and use FTP to transfer the
archive to ftp://ftp.mysql.com/pub/mysql/upload/. Then enter
the problem into our bugs database at http://bugs.mysql.com/.
mysqld
server as well as the options that you use to run any MySQL client programs.
The options to programs such as mysqld and mysql, and to the
configure script, are often keys to answers and are very relevant.
It is never a bad idea to include them. If you use any modules, such
as Perl or PHP, please include the version numbers of those as well.
mysqlaccess, the output of mysqladmin reload, and all
the error messages you get when trying to connect. When you test your
privileges, you should first run mysqlaccess. After this, execute
mysqladmin reload version and try to connect with the program that
gives you trouble. mysqlaccess can be found in the `bin'
directory under your MySQL installation directory.
parse error, please check your syntax closely. If
you can't find something wrong with it, it's extremely likely that your
current version of MySQL Server doesn't support the syntax you are
using. If you are using the current version and the manual at
http://dev.mysql.com/doc/ doesn't cover the
syntax you are using, MySQL Server doesn't support your query. In this
case, your only options are to implement the syntax yourself or email
licensing@mysql.com and ask for an offer to implement it.
If the manual covers the syntax you are using, but you have an older version
of MySQL Server, you should check the MySQL change history to see
when the syntax was implemented. In this case, you have the option of
upgrading to a newer version of MySQL Server. See section C MySQL Change History.
CHECK TABLE and REPAIR TABLE
or with myisamchk.
See section 5 Database Administration.
If you are running Windows, please verify that lower_case_table_names
is 1 or 2 with SHOW VARIABLES LIKE 'lower_case_table_names'.
mysqld should never crash a table if nothing killed it in the
middle of an update. If you can find the cause of mysqld dying,
it's much easier for us to provide you with a fix for the problem.
See section A.1 How to Determine What Is Causing a Problem.