MySQL Reference Manual

Speed enhancements

Embedded MySQL Server introduced

InnoDB storage engine as standard

New functionality

Standards compliance, portability, and migration

Internationalization

Usability enhancements

In the process of implementing features for new users, we have not forgotten requests from our loyal community of existing users.

Support for subqueries and derived tables

Speed enhancements

New functionality

Standards compliance, portability, and migration

Internationalization and Localization

Usability enhancements

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Start by searching the MySQL online manual at http://dev.mysql.com/doc/. We try to keep the manual up to date by updating it frequently with solutions to newly found problems. The change history (http://dev.mysql.com/doc/mysql/en/News.html) can be particularly useful since it is quite possible that a newer version contains a solution to your problem.

Search in the bugs database at http://bugs.mysql.com/ to see whether the bug has been reported and fixed.

Search the MySQL mailing list archives at http://lists.mysql.com/.

You can also use http://www.mysql.com/search/ to search all the Web pages (including the manual) that are located at the MySQL AB Web site.

The version number of the MySQL distribution you are using (for example, MySQL 4.0.12). You can find out which version you are running by executing mysqladmin version. The mysqladmin program can be found in the bin directory under your MySQL installation directory.

The manufacturer and model of the machine on which you experience the problem.

The operating system name and version. If you work with Windows, you can usually get the name and version number by double-clicking your My Computer icon and pulling down the ``Help/About Windows'' menu. For most Unix-like operating systems, you can get this information by executing the command uname -a.

Sometimes the amount of memory (real and virtual) is relevant. If in doubt, include these values.

If you are using a source distribution of the MySQL software, the name and version number of the compiler used are needed. If you have a binary distribution, the distribution name is needed.

If the problem occurs during compilation, include the exact error messages and also a few lines of context around the offending code in the file where the error occurs.

If 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 E.1.5, “Using Log Files to Find Cause of Errors in mysqld”.

If a database table is related to the problem, include the output from 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 helps us create a situation matching the one you have experienced.

For speed-related bugs or problems with 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>

If a bug or problem occurs while running mysqld, try to provide an input script that reproduces 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.

If you can't produce a test case with only a few rows, or if the test table is too big to be mailed to the mailing list (more than 10 rows), you should dump your tables using 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/.

If you think that the MySQL server produces a strange result from a query, include not only the result, but also your opinion of what the result should be, and an account describing the basis for your opinion.

When giving an example of the problem, it's better to use the variable names, table names, and so on that exist in your actual situation than to come up with new names. The problem could be related to the name of a variable or table. These cases are rare, perhaps, but it is better to be safe than sorry. After all, it should be easier for you to provide an example that uses your actual situation, and it is by all means better for us. In case you have data that you don't want to show to others, you can use FTP to transfer it to ftp://ftp.mysql.com/pub/mysql/upload/. If the information is really top secret and you don't want to show it even to us, then go ahead and provide an example using other names, but please regard this as the last choice.

Include all the options given to the relevant programs, if possible. For example, indicate the options that you use when you start the 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.

If your question is related to the privilege system, please include the output of 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.

If you have a patch for a bug, do include it. But don't assume that the patch is all we need, or that we can use it, if you don't provide some necessary information such as test cases showing the bug that your patch fixes. We might find problems with your patch or we might not understand it at all; if so, we can't use it.

If we can't verify exactly what the purpose of the patch is, we won't use it. Test cases help us here. Show that the patch handles all the situations that may occur. If we find a borderline case (even a rare one) where the patch won't work, it may be useless.

Guesses about what the bug is, why it occurs, or what it depends on are usually wrong. Even the MySQL team can't guess such things without first using a debugger to determine the real cause of a bug.

Indicate in your bug report that you have checked the reference manual and mail archive so that others know you have tried to solve the problem yourself.

If you get a 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 Appendix D, MySQL Change History.

If your problem is that your data appears corrupt or you get errors when you access a particular table, you should first check and then try to repair your tables with CHECK TABLE and REPAIR TABLE or with myisamchk. See Chapter 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'.

If you often get corrupted tables, you should try to find out when and why this happens. In this case, the error log in the MySQL data directory may contain some information about what happened. (This is the file with the .err suffix in the name.) See Section 5.9.1, “The Error Log”. Please include any relevant information from this file in your bug report. Normally 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”.

If possible, download and install the most recent version of MySQL Server and check whether it solves your problem. All versions of the MySQL software are thoroughly tested and should work without problems. We believe in making everything as backward-compatible as possible, and you should be able to switch MySQL versions without difficulty. See Section 2.1.2, “Choosing Which MySQL Distribution to Install”.

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

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

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 are 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 depends 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 has been changed by another user.'' Then we show the old row versus the new row in a window so that the user can decide which version of the customer record to 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+125;
UPDATE customer
  SET
    customer_date='current_date',
    address='new address',
    phone='new phone',
    money_owed_to_us=money_owed_to_us-125
  WHERE
    customer_id=id AND address='old address' AND phone='old phone';

This is very efficient and works even if another client has changed the values in the pay_back or money_owed_to_us columns.

In many cases, users have wanted LOCK TABLES and/or ROLLBACK for the purpose of managing unique identifiers. This can be handled much more efficiently without locking or rolling back by using an AUTO_INCREMENT column and either the LAST_INSERT_ID() SQL function or the mysql_insert_id() C API function. See Section 12.8.3, “Information Functions”. See Section 22.2.3.33, “mysql_insert_id()”.

You can generally code around the need for row-level locking. Some situations really do need it, and InnoDB tables support row-level locking. With MyISAM tables, you can use a flag column in the table and do something like the following:

UPDATE tbl_name SET row_flag=1 WHERE id=ID;

MySQL returns 1 for the number of affected rows if the row was found and row_flag wasn't 1 in the original row.

You can think of it as though MySQL Server changed the preceding query to:

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

Assuming proper design of the relationships, foreign key constraints make it more difficult for a programmer to introduce an inconsistency into the database.

Centralized checking of constraints by the database server makes it unnecessary to perform these checks on the application side. This eliminates the possibility that different applications may not all check the constraints in the same way.

Using cascading updates and deletes can simplify the application code.

Properly designed foreign key rules aid in documenting relationships between tables.

In the absence of server-side foreign key relationship checking, the application itself must handle relationship issues. For example, it must take care to insert rows into tables in the proper order, and to avoid creating orphaned child records. It must also be able to recover from errors that occur in the middle of multiple-record insert operations.

If ON DELETE is the only referential integrity capability an application needs, note that as of MySQL Server 4.0, you can use multiple-table DELETE statements to delete rows from many tables with a single statement. See Section 13.1.1, “DELETE Syntax”.

A workaround for the lack of ON DELETE is to add the appropriate DELETE statement to your application when you delete records from a table that has a foreign key. In practice, this is often as quick as using foreign keys, and is more portable.

Foreign key support addresses many referential integrity issues, but it is still necessary to design key relationships carefully to avoid circular rules or incorrect combinations of cascading deletes.

It is not uncommon for a DBA to create a topology of relationships that makes it difficult to restore individual tables from a backup. (MySQL alleviates this difficulty by allowing you to temporarily disable foreign key checks when reloading a table that depends on other tables. See Section 15.7.4, “FOREIGN KEY Constraints”. As of MySQL 4.1.1, mysqldump generates dump files that take advantage of this capability automatically when reloaded.)

If you try to store an out of range value in a numeric column, MySQL Server instead stores zero, the smallest possible value, or the largest possible value in the column.

For strings, MySQL stores either the empty string or the longest possible string that can be in the column.

If you try to store a string that doesn't start with a number into a numeric column, MySQL Server stores 0.

If you try to store NULL into a column that doesn't take NULL values, MySQL Server stores 0 or '' (the empty string) instead.

MySQL allows you to store certain incorrect date values into DATE and DATETIME columns (such as '2000-02-31' or '2000-02-00'). The idea is that it's not the job of the SQL server to validate dates. If MySQL can store a date value and retrieve exactly the same value, MySQL stores it as given. If the date is totally wrong (outside the server's ability to store it), the special date value '0000-00-00' is stored in the column instead.

If an INSERT statement specifies no value for a column, MySQL inserts its default value if the column definition includes an explicit DEFAULT clause. If the definition has no such DEFAULT clause, MySQL inserts the implicit default value for the column data type. In general, this is the empty string for string columns, 0 for numeric columns, and '0000-00-00' for date columns. Implicit default values are discussed in Section 13.2.6, “CREATE TABLE Syntax”.

An ENUM value must be one of those listed in the column definition, or the internal numeric equivalent thereof. The value cannot be the error value (that is, 0 or the empty string). For a column defined as ENUM('a','b','c'), values such as '', 'd', and 'ax' are illegal and are rejected.

A SET value must be the empty string or a value consisting of one or more of the values listed in the column definition separated by commas. For a column defined as SET('a','b','c'), values such as 'd', and 'a,b,c,d' are illegal and are rejected.

You should avoid using spaces at the end of column names because this can cause weird behavior. (Fixed in MySQL 4.0.) (Bug #4196)

You can get a deadlock (hung thread) if you use LOCK TABLE to lock multiple tables and then in the same connection use DROP TABLE to drop one of them while another thread is trying to lock it. (To break the deadlock, you can use KILL to terminate any of the threads involved.) This issue is resolved as of MySQL 4.0.12.

SELECT MAX(key_column) FROM t1,t2,t3... where one of the tables are empty doesn't return NULL but instead returns the maximum value for the column. This issue is resolved as of MySQL 4.0.11.

DELETE FROM heap_table without a WHERE clause doesn't work on a locked HEAP table.

In HAVING you can get a crash or wrong result if you use an alias to a RAND() function. This is fixed in 4.1.10 but will not be fixed in 4.0 because the fix 'may' cause side effects for some applications.

In a UNION, the first SELECT determines the type, max_length, and NULL properties for the resulting columns. This issue is resolved as of MySQL 4.1.1; the property values are based on the rows from all UNION parts.

In DELETE with many tables, you can't refer to tables to be deleted through an alias. This is fixed as of MySQL 4.1.

You cannot mix UNION ALL and UNION DISTINCT in the same query. If you use ALL for one UNION, it is used for all of them. This is fixed as of MySQL 4.1.2. The rules for mixed UNION types are given in Section 13.1.7.2, “UNION Syntax”.

FLUSH TABLES WITH READ LOCK does not block CREATE TABLE, which may cause a problem with the binary log position when doing a full backup of tables and the binary log.

mysqldump --single-transaction --master-data behaved like mysqldump --master-data, so the dump was a blocking one. This is fixed starting from MySQL 4.1.8.

When using the RPAD() function (or any function adding spaces to the right) in a query that had to be resolved by using a temporary table, all resulting strings had rightmost spaces removed (i.e. RPAD() did not work).

If you compare a NULL value to a subquery using ALL/ANY/SOME and the subquery returns an empty result, the comparison might evaluate to the non-standard result of NULL rather than to TRUE or FALSE. This will be fixed in MySQL 5.0.

Even if you are using lower_case_table_names=2 (which enables MySQL to remember the used case for databases and table names) MySQL does not remember the used case for database names for the function DATABASE() or in various logs (on case-insensitive systems).

Dropping a FOREIGN KEY constraint doesn't work in replication because the constraint may have another name on the slave.

REPLACE (and LOAD DATA with the REPLACE option) does not trigger ON DELETE CASCADE.

DISTINCT with ORDER BY doesn't work inside GROUP_CONCAT() if you don't use all and only those columns that are in the DISTINCT list.

If one user has a long-running transaction and another user drops a table that is updated in the transaction, there is small chance that the binary log may contain the DROP TABLE command before the table is used in the transaction itself. We plan to fix this by having the DROP TABLE wait until the table is not used in any transaction.

When inserting a big integer value (between 2^63 and 2^64−1) into a decimal/string column, it is inserted as a negative value because the number is evaluated in a signed integer context.

FLUSH TABLES WITH READ LOCK does not block COMMIT if the server is running without binary logging, which may cause a problem (of consistency between tables) when doing a full backup.

ANALYZE TABLE on a BDB table may in some cases make the table unusable until you restart mysqld. If this happens, look for errors of the following form in the MySQL error file:

001207 22:07:56  bdb:  log_flush: LSN past current end-of-log

Don't execute ALTER TABLE on a BDB table on which you are running multiple-statement transactions until all those transactions complete. (The transaction might be ignored.)

ANALYZE TABLE, OPTIMIZE TABLE, and REPAIR TABLE may cause problems on tables for which you are using INSERT DELAYED.

Doing a LOCK TABLE ... and FLUSH TABLES ... doesn't guarantee that there isn't a half-finished transaction in progress on the table.

BDB tables are a bit slow to open. If you have many BDB tables in a database, it takes a long time to use the mysql client on the database if you are not using the -A option or if you are using rehash. This is especially notable when you have a large table cache.

Replication uses query-level logging: The master writes the executed queries to the binary log. This is a very fast, compact, and efficient logging method that works perfectly in most cases. Still it is possible for the data on the master and slave to become different if a query is designed in such a way that the data modification is non-deterministic; that is, left to the will of the query optimizer. (That generally is not a good practice anyway, even outside of replication!) For example:

If and only if all these queries have no ORDER BY clause guaranteeing a deterministic order.

For example, for INSERT ... SELECT with no ORDER BY, the SELECT may return rows in a different order (which results in a row having different ranks, hence getting a different number in the AUTO_INCREMENT column), depending on the choices made by the optimizers on the master and slave. A query is optimized differently on the master and slave only if:

This problem may also affect database restoration using mysqlbinlog|mysql.

The easiest way to avoid this problem in all cases is to add an ORDER BY clause to such non-deterministic queries to ensure that the rows are always stored or modified in the same order. In future MySQL versions, we will automatically add an ORDER BY clause when needed.

Log filenames are based on the server hostname (if you don't specify a filename with the startup option). You have to use options like --log-bin=old_host_name-bin if you change your hostname to something else. Another option is to just rename the old files to reflect your hostname change (and if these are binary logs, you also need to edit the binary log index file and fix the binlog names there). See Section 5.2.1, “mysqld Command-Line Options”.

mysqlbinlog does not delete temporary files left after a LOAD DATA INFILE command. See Section 8.5, “The mysqlbinlog Binary Log Utility”.

RENAME doesn't work with TEMPORARY tables or tables used in a MERGE table.

Due to the way table definition files are stored, you cannot use character 255 (CHAR(255)) in table names, column names, or enumerations. This is scheduled to be fixed in version 5.1 when we have new table definition format files.

When using SET CHARACTER SET, you can't use translated characters in database, table, and column names.

You can't use '_' or '%' with ESCAPE in LIKE ... ESCAPE.

If you have a DECIMAL column in which the same number is stored in different formats (for example, +01.00, 1.00, 01.00), GROUP BY may regard each value as a different value.

You cannot build the server in another directory when using MIT-pthreads. Because this requires changes to MIT-pthreads, we are not likely to fix this. See Section 2.8.5, “MIT-pthreads Notes”.

BLOB and TEXTvalues can't ``reliably'' be used in GROUP BY or ORDER BY or DISTINCT. Only the first max_sort_length bytes are used when comparing BLOB values in these cases. The default value of max_sort_length value is 1024. It can be changed at server startup time. As of MySQL 4.0.3, it can also be changed at runtime. For older versions, a workaround for most cases is to use a substring. For example:

SELECT DISTINCT LEFT(blob_col,2048) FROM tbl_name;

Numeric calculations are done with BIGINT or DOUBLE (both are normally 64 bits long). Which precision you get depends on the function. The general rule is that bit functions are done with BIGINT precision, IF and ELT() with BIGINT or DOUBLE precision, and the rest with DOUBLE precision. You should try to avoid using unsigned long long values if they resolve to be bigger than 63 bits (9223372036854775807) for anything other than bit fields. MySQL Server 4.0 has better BIGINT handling than 3.23.

All string columns, except BLOB and TEXT columns, automatically have all trailing spaces removed when retrieved. For CHAR types, this is okay. The bug is that in MySQL Server, VARCHAR columns are treated the same way.

You can have only up to 255 ENUM and SET columns in one table.

In MIN(), MAX(), and other aggregate functions, MySQL currently compares ENUM and SET columns by their string value rather than by the string's relative position in the set.

mysqld_safe redirects all messages from mysqld to the mysqld log. One problem with this is that if you execute mysqladmin refresh to close and reopen the log, stdout and stderr are still redirected to the old log. If you use --log extensively, you should edit mysqld_safe to log to host_name.err instead of host_name.log so that you can easily reclaim the space for the old log by deleting the old one and executing mysqladmin refresh.

In the UPDATE statement, columns are updated from left to right. If you refer to an updated column, you get the updated value instead of the original value. For example, the following statement increments KEY by 2, not 1:

mysql> UPDATE tbl_name SET KEY=KEY+1,KEY=KEY+1;

You can refer to multiple temporary tables in the same query, but you cannot refer to any given temporary table more than once. For example, the following doesn't work:

mysql> SELECT * FROM temp_table, temp_table AS t2;
ERROR 1137: Can't reopen table: 'temp_table'

The optimizer may handle DISTINCT differently when you are using ``hidden'' columns in a join than when you are not. In a join, hidden columns are counted as part of the result (even if they are not shown), whereas in normal queries, hidden columns don't participate in the DISTINCT comparison. We will probably change this in the future to never compare the hidden columns when executing DISTINCT.

An example of this is:

SELECT DISTINCT mp3id FROM band_downloads
       WHERE userid = 9 ORDER BY id DESC;

and

SELECT DISTINCT band_downloads.mp3id
       FROM band_downloads,band_mp3
       WHERE band_downloads.userid = 9
       AND band_mp3.id = band_downloads.mp3id
       ORDER BY band_downloads.id DESC;

In the second case, you might in MySQL Server 3.23.x get two identical rows in the result set (because the values in the hidden id column may differ).

Note that this happens only for queries where you don't have the ORDER BY columns in the result.

Because MySQL Server allows you to work with table types that don't support transactions, and thus can't roll back data, some things behave a little differently in MySQL Server than in other SQL servers. This is just to ensure that MySQL Server never needs to do a rollback for an SQL statement. This may be a little awkward at times because column values must be checked in the application, but this actually gives you a nice speed increase because it allows MySQL Server to do some optimizations that otherwise would be very hard to do.

If you set a column to an incorrect value, MySQL Server, instead of doing a rollback, stores the ``best possible value'' in the column. For information about how this occurs, see Section 1.5.6, “How MySQL Deals with Constraints”.

If you execute a PROCEDURE on a query that returns an empty set, in some cases the PROCEDURE does not transform the columns.

Creation of a table of type MERGE doesn't check whether the underlying tables are of compatible types.

If you use ALTER TABLE first to add a UNIQUE index to a table used in a MERGE table and then to add a normal index on the MERGE table, the key order is different for the tables if there was an old key that was not unique in the table. This is because ALTER TABLE puts UNIQUE indexes before normal indexes to be able to detect duplicate keys as early as possible.

In the following case you can get a core dump:

Before MySQL Server 3.23.2, an UPDATE that updated a key with a WHERE on the same key may have failed because the key was used to search for records and the same row may have been found multiple times:

UPDATE tbl_name SET KEY=KEY+1 WHERE KEY > 100;

A workaround is to use:

UPDATE tbl_name SET KEY=KEY+1 WHERE KEY+0 > 100;

This works because MySQL Server does not use an index on expressions in the WHERE clause.

Before MySQL Server 3.23, all numeric types were treated as fixed-point fields. That means that you had to specify how many decimals a floating-point field should have. All results were returned with the correct number of decimals.

MySQL 5.0 is the newest development release series and is under very active development for new features. Alpha releases have been issued to allow more widespread testing.

MySQL 4.1 is the current stable (production-quality) release series. New releases are issued for bugfixes. No new features are added that could diminish the code stability.

MySQL 4.0 is the previous stable (production-quality) release series. New releases are issued for bugfixes. No new features are added that could diminish the code stability.

MySQL 3.23 is the old stable (production-quality) release series. This series is retired, so new releases are issued only to fix critical bugs.

The first number (4) is the major version and also describes the file format. All Version 4 releases have the same file format.

The second number (1) is the release level. Taken together, the major version and release level constitute the release series number.

The third number (2) is the version number within the release series. This is incremented for each new release. Usually you want the latest version for the series you have chosen.

alpha indicates that the release contains some large section of new code that hasn't been 100% tested. Known bugs (usually there are none) should be documented in the News section. See Appendix D, MySQL Change History. There are also new commands and extensions in most alpha releases. Active development that may involve major code changes can occur in an alpha release, but everything is tested before issuing a release. For this reason, there should be no known bugs in any MySQL release.

beta means that all new code has been tested. No major new features that could cause corruption in old code are added. There should be no known bugs. A version changes from alpha to beta when there haven't been any reported fatal bugs within an alpha version for at least a month and we have no plans to add any features that could make any old command unreliable.

gamma is a beta that has been around a while and seems to work fine. Only minor fixes are added. This is what many other companies call a release.

If there is no suffix, it means that the version has been run for a while at many different sites with no reports of bugs other than platform-specific bugs. Only critical bugfixes are applied to the release. This is what we call a production (stable) or `General Availability' (GA) release.

An internal test suite

The mysql-test directory contains an extensive set of test cases. We run these tests for virtually every server binary. See Section 25.1.2, “MySQL Test Suite” for more information about this test suite.

The MySQL benchmark suite

This suite 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 7.1.4, “The MySQL Benchmark Suite”.

The crash-me test

This test tries to determine what features the database supports and what its capabilities and limitations are. See Section 7.1.4, “The MySQL Benchmark Suite”.

Binary distributions generally are easier to install than source distributions.

To satisfy different user requirements, we provide two different binary versions: one compiled with the non-transactional storage engines (a small, fast binary), and one configured with the most important extended options like transaction-safe tables. Both versions are compiled from the same source distribution. All native MySQL clients can connect to servers from either MySQL version.

The extended MySQL binary distribution is marked with the -max suffix and is configured with the same options as mysqld-max. See Section 5.1.2, “The mysqld-max Extended MySQL Server”.

If you want to use the MySQL-Max RPM, you must first install the standard MySQL-server RPM.

You want to install MySQL at some explicit location. The standard binary distributions are ``ready to run'' at any place, but you may want to have even more flexibility to place MySQL components where you want.

You want to configure mysqld with some extra features that are not included in the standard binary distributions. Here is a list of the most common extra options that you may want to use:

You want to configure mysqld without some features that are included in the standard binary distributions. For example, distributions normally are compiled with support for all character sets. If you want a smaller MySQL server, you can recompile it with support for only the character sets you need.

You have a special compiler (such as pgcc) or want to use compiler options that are better optimized for your processor. Binary distributions are compiled with options that should work on a variety of processors from the same processor family.

You want to use the latest sources from one of the BitKeeper repositories to have access to all current bugfixes. For example, if you have found a bug and reported it to the MySQL development team, the bugfix is committed to the source repository and you can access it there. The bugfix does not appear in a release until a release actually is issued.

You want to read (or modify) the C and C++ code that makes up MySQL. For this purpose, you should get a source distribution, because the source code is always the ultimate manual.

Source distributions contain more tests and examples than binary distributions.

Releases are issued within each series. For each release, the last number in the version is one more than the previous release within the same series.

Production (stable) releases are meant to appear about 1-2 times a year. However, if small bugs are found, a release with only bugfixes is issued.

Working releases/bugfixes to old releases are meant to appear about every 4-8 weeks.

Binary distributions for some platforms are made by us for major releases. Other people may make binary distributions for other systems, but probably less frequently.

We make fixes available as soon as we have identified and corrected small or non-critical but annoying bugs. The fixes are available immediately from our public BitKeeper repositories, and will be included in the next release.

If by any chance a fatal bug is found in a release, we make a new release as soon as possible. (We would like other companies to do this, too!)

We monitor bugs from our customer support list, the bugs database at http://bugs.mysql.com/, and the MySQL external mailing lists.

All reported bugs for live versions are entered into the bugs database.

When we fix a bug, we always try to make a test case for it and include it into our test system to ensure that the bug can never recur without being detected. (About 90% of all fixed bugs have a test case.)

We create test cases for all new features we add to MySQL.

Before we start to build a new MySQL release, we ensure that all reported repeatable bugs for the MySQL version (3.23.x, 4.0.x, etc) are fixed. If something is impossible to fix (due to some internal design decision in MySQL), we document this in the manual. See Section 1.5.7, “Known Errors and Design Deficiencies in MySQL”.

We do a build on all platforms for which we support binaries (15+ platforms) and run our test suite and benchmark suite on all of them.

We do not publish a binary for a platform for which the test or benchmark suite fails. If the problem is due to a general error in the source, we fix it and do the build plus tests on all systems again from scratch.

The build and test process takes 2-3 days. If we receive a report regarding a fatal bug during this process (for example, one that causes a core dump), we fix the problem and restart the build process.

After publishing the binaries on http://dev.mysql.com/, we send out an announcement message to the mysql and announce mailing lists. See Section 1.4.1.1, “The MySQL Mailing Lists”. The announcement message contains a list of all changes to the release and any known problems with the release. The Known Problems section in the release notes has been needed for only a handful of releases.

To quickly give our users access to the latest MySQL features, we do a new MySQL release every 4-8 weeks. Source code snapshots are built daily and are available at http://downloads.mysql.com/snapshots.php.

If, despite our best efforts, we get any bug reports after the release is done that there was something critically wrong with the build on a specific platform, we fix it at once and build a new 'a' release for that platform. Thanks to our large user base, problems are found quickly.

Our track record for making stable releases is quite good. In the last 150 releases, we had to do a new build for fewer than 10 releases. In three of these cases, the bug was a faulty glibc library on one of our build machines that took us a long time to track down.

Linux 2.4.xx x86 with gcc 2.95.3:

CFLAGS="-O2 -mcpu=pentiumpro" CXX=gcc CXXFLAGS="-O2 -mcpu=pentiumpro -felide-constructors" ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile --enable-assembler --disable-shared --with-client-ldflags=-all-static --with-mysqld-ldflags=-all-static

Linux 2.4.x x86 with icc (Intel C++ Compiler 8.0):

CC=icc CXX=icc CFLAGS="-O3 -unroll2 -ip -mp -no-gcc -restrict" CXXFLAGS="-O3 -unroll2 -ip -mp -no-gcc -restrict" ./configure --prefix=/usr/local/mysql --localstatedir=/usr/local/mysql/data --libexecdir=/usr/local/mysql/bin --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile --enable-assembler --disable-shared --with-client-ldflags=-all-static --with-mysqld-ldflags=-all-static --with-embedded-server --with-innodb

Linux 2.4.xx Intel Itanium 2 with ecc (Intel C++ Itanium Compiler 7.0):

CC=ecc CFLAGS="-O2 -tpp2 -ip -nolib_inline" CXX=ecc CXXFLAGS="-O2 -tpp2 -ip -nolib_inline" ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile

Linux 2.4.xx Intel Itanium with ecc (Intel C++ Itanium Compiler 7.0):

CC=ecc CFLAGS=-tpp1 CXX=ecc CXXFLAGS=-tpp1 ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile

Linux 2.4.xx alpha with ccc (Compaq C V6.2-505 / Compaq C++ V6.3-006):

CC=ccc CFLAGS="-fast -arch generic" CXX=cxx CXXFLAGS="-fast -arch generic -noexceptions -nortti" ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile --with-mysqld-ldflags=-non_shared --with-client-ldflags=-non_shared --disable-shared

Linux 2.x.xx ppc with gcc 2.95.4:

CC=gcc CFLAGS="-O3 -fno-omit-frame-pointer" CXX=gcc CXXFLAGS="-O3 -fno-omit-frame-pointer -felide-constructors -fno-exceptions -fno-rtti" ./configure --prefix=/usr/local/mysql --localstatedir=/usr/local/mysql/data --libexecdir=/usr/local/mysql/bin --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile --disable-shared --with-embedded-server --with-innodb

Linux 2.4.xx s390 with gcc 2.95.3:

CFLAGS="-O2" CXX=gcc CXXFLAGS="-O2 -felide-constructors" ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile --disable-shared --with-client-ldflags=-all-static --with-mysqld-ldflags=-all-static

Linux 2.4.xx x86_64 (AMD64) with gcc 3.2.1:

CXX=gcc ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile --disable-shared

Sun Solaris 8 x86 with gcc 3.2.3:

CC=gcc CFLAGS="-O3 -fno-omit-frame-pointer" CXX=gcc CXXFLAGS="-O3 -fno-omit-frame-pointer -felide-constructors -fno-exceptions -fno-rtti" ./configure --prefix=/usr/local/mysql --localstatedir=/usr/local/mysql/data --libexecdir=/usr/local/mysql/bin --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile --disable-shared --with-innodb

Sun Solaris 8 SPARC with gcc 3.2:

CC=gcc CFLAGS="-O3 -fno-omit-frame-pointer" CXX=gcc CXXFLAGS="-O3 -fno-omit-frame-pointer -felide-constructors -fno-exceptions -fno-rtti" ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile --enable-assembler --with-named-z-libs=no --with-named-curses-libs=-lcurses --disable-shared

Sun Solaris 8 SPARC 64-bit with gcc 3.2:

CC=gcc CFLAGS="-O3 -m64 -fno-omit-frame-pointer" CXX=gcc CXXFLAGS="-O3 -m64 -fno-omit-frame-pointer -felide-constructors -fno-exceptions -fno-rtti" ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile --with-named-z-libs=no --with-named-curses-libs=-lcurses --disable-shared

Sun Solaris 9 SPARC with gcc 2.95.3:

CC=gcc CFLAGS="-O3 -fno-omit-frame-pointer" CXX=gcc CXXFLAGS="-O3 -fno-omit-frame-pointer -felide-constructors -fno-exceptions -fno-rtti" ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile --enable-assembler --with-named-curses-libs=-lcurses --disable-shared

Sun Solaris 9 SPARC with cc-5.0 (Sun Forte 5.0):

CC=cc-5.0 CXX=CC ASFLAGS="-xarch=v9" CFLAGS="-Xa -xstrconst -mt -D_FORTEC_ -xarch=v9" CXXFLAGS="-noex -mt -D_FORTEC_ -xarch=v9" ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile --enable-assembler --with-named-z-libs=no --enable-thread-safe-client --disable-shared

IBM AIX 4.3.2 ppc with gcc 3.2.3:

CFLAGS="-O2 -mcpu=powerpc -Wa,-many " CXX=gcc CXXFLAGS="-O2 -mcpu=powerpc -Wa,-many -felide-constructors -fno-exceptions -fno-rtti" ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile --with-named-z-libs=no --disable-shared

IBM AIX 4.3.3 ppc with xlC_r (IBM Visual Age C/C++ 6.0):

CC=xlc_r CFLAGS="-ma -O2 -qstrict -qoptimize=2 -qmaxmem=8192" CXX=xlC_r CXXFLAGS ="-ma -O2 -qstrict -qoptimize=2 -qmaxmem=8192" ./configure --prefix=/usr/local/mysql --localstatedir=/usr/local/mysql/data --libexecdir=/usr/local/mysql/bin --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile --with-named-z-libs=no --disable-shared --with-innodb

IBM AIX 5.1.0 ppc with gcc 3.3:

CFLAGS="-O2 -mcpu=powerpc -Wa,-many" CXX=gcc CXXFLAGS="-O2 -mcpu=powerpc -Wa,-many -felide-constructors -fno-exceptions -fno-rtti" ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile --with-named-z-libs=no --disable-shared

IBM AIX 5.2.0 ppc with xlC_r (IBM Visual Age C/C++ 6.0):

CC=xlc_r CFLAGS="-ma -O2 -qstrict -qoptimize=2 -qmaxmem=8192" CXX=xlC_r CXXFLAGS="-ma -O2 -qstrict -qoptimize=2 -qmaxmem=8192" ./configure --prefix=/usr/local/mysql --localstatedir=/usr/local/mysql/data --libexecdir=/usr/local/mysql/bin --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile --with-named-z-libs=no --disable-shared --with-embedded-server --with-innodb

HP-UX 10.20 pa-risc1.1 with gcc 3.1:

CFLAGS="-DHPUX -I/opt/dce/include -O3 -fPIC" CXX=gcc CXXFLAGS="-DHPUX -I/opt/dce /include -felide-constructors -fno-exceptions -fno-rtti -O3 -fPIC" ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile --with-pthread --with-named-thread-libs=-ldce --with-lib-ccflags=-fPIC --disable-shared

HP-UX 11.00 pa-risc with aCC (HP ANSI C++ B3910B A.03.50):

CC=cc CXX=aCC CFLAGS=+DAportable CXXFLAGS=+DAportable ./configure --prefix=/usr/local/mysql --localstatedir=/usr/local/mysql/data --libexecdir=/usr/local/mysql/bin --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile --disable-shared --with-embedded-server --with-innodb

HP-UX 11.11 pa-risc2.0 64bit with aCC (HP ANSI C++ B3910B A.03.33):

CC=cc CXX=aCC CFLAGS=+DD64 CXXFLAGS=+DD64 ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile --disable-shared

HP-UX 11.11 pa-risc2.0 32bit with aCC (HP ANSI C++ B3910B A.03.33):

CC=cc CXX=aCC CFLAGS="+DAportable" CXXFLAGS="+DAportable" ./configure --prefix=/usr/local/mysql --localstatedir=/usr/local/mysql/data --libexecdir=/usr/local/mysql/bin --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile --disable-shared --with-innodb

HP-UX 11.22 ia64 64bit with aCC (HP aC++/ANSI C B3910B A.05.50):

CC=cc CXX=aCC CFLAGS="+DD64 +DSitanium2" CXXFLAGS="+DD64 +DSitanium2" ./configure --prefix=/usr/local/mysql --localstatedir=/usr/local/mysql/data --libexecdir=/usr/local/mysql/bin --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile --disable-shared --with-embedded-server --with-innodb

Apple Mac OS X 10.2 powerpc with gcc 3.1:

CC=gcc CFLAGS="-O3 -fno-omit-frame-pointer" CXX=gcc CXXFLAGS="-O3 -fno-omit-frame-pointer -felide-constructors -fno-exceptions -fno-rtti" ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile --disable-shared

FreeBSD 4.7 i386 with gcc 2.95.4:

CFLAGS=-DHAVE_BROKEN_REALPATH ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile --enable-assembler --with-named-z-libs=not-used --disable-shared

FreeBSD 4.7 i386 using LinuxThreads with gcc 2.95.4:

CFLAGS="-DHAVE_BROKEN_REALPATH -D__USE_UNIX98 -D_REENTRANT -D_THREAD_SAFE -I/usr/local/include/pthread/linuxthreads" CXXFLAGS="-DHAVE_BROKEN_REALPATH -D__USE_UNIX98 -D_REENTRANT -D_THREAD_SAFE -I/usr/local/include/pthread/linuxthreads" ./configure --prefix=/usr/local/mysql --localstatedir=/usr/local/mysql/data --libexecdir=/usr/local/mysql/bin --enable-thread-safe-client --enable-local-infile --enable-assembler --with-named-thread-libs="-DHAVE_GLIBC2_STYLE_GETHOSTBYNAME_R -D_THREAD_SAFE -I /usr/local/include/pthread/linuxthreads -L/usr/local/lib -llthread -llgcc_r" --disable-shared --with-embedded-server --with-innodb

QNX Neutrino 6.2.1 i386 with gcc 2.95.3qnx-nto 20010315:

CC=gcc CFLAGS="-O3 -fno-omit-frame-pointer" CXX=gcc CXXFLAGS="-O3 -fno-omit-frame-pointer -felide-constructors -fno-exceptions -fno-rtti" ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile --disable-shared

SCO Unix 3.2v5.0.6 i386 with gcc 2.95.3:

CFLAGS="-O3 -mpentium" LDFLAGS=-static CXX=gcc CXXFLAGS="-O3 -mpentium -felide-constructors" ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile --with-named-z-libs=no --enable-thread-safe-client --disable-shared

SCO OpenUnix 8.0.0 i386 with CC 3.2:

CC=cc CFLAGS="-O" CXX=CC ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile --with-named-z-libs=no --enable-thread-safe-client --disable-shared

Compaq Tru64 OSF/1 V5.1 732 alpha with cc/cxx (Compaq C V6.3-029i / DIGITAL C++ V6.1-027):

CC="cc -pthread" CFLAGS="-O4 -ansi_alias -ansi_args -fast -inline speed -speculate all" CXX="cxx -pthread" CXXFLAGS="-O4 -ansi_alias -fast -inline speed -speculate all -noexceptions -nortti" ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile --with-named-thread-libs="-lpthread -lmach -lexc -lc" --disable-shared --with-mysqld-ldflags=-all-static

SGI Irix 6.5 IP32 with gcc 3.0.1:

CC=gcc CFLAGS="-O3 -fno-omit-frame-pointer" CXXFLAGS="-O3 -fno-omit-frame-pointer -felide-constructors -fno-exceptions -fno-rtti" ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile --disable-shared

FreeBSD/sparc64 5.0 with gcc 3.2.1:

CFLAGS=-DHAVE_BROKEN_REALPATH ./configure --prefix=/usr/local/mysql --localstatedir=/usr/local/mysql/data --libexecdir=/usr/local/mysql/bin --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile --disable-shared --with-innodb

Linux 2.2.xx SPARC with egcs 1.1.2:

CC=gcc CFLAGS="-O3 -fno-omit-frame-pointer" CXX=gcc CXXFLAGS="-O3 -fno-omit-frame-pointer -felide-constructors -fno-exceptions -fno-rtti" ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex --enable-thread-safe-client --enable-local-infile --enable-assembler --disable-shared

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-charsets=complex

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

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

AIX 4.2 with gcc 2.7.2.2:

CC=gcc CXX=gcc CXXFLAGS=-O3 ./configure --prefix=/usr/local/mysql --with-extra-charsets=complex

MySQL Command Line Client: This is a shortcut to the mysql command-line client and is configured to connect as the root user. The shortcut prompts for a root user password when connecting.

MySQL Server Instance Config Wizard: This is a shortcut to the MySQL Configuration Wizard. Use this shortcut to configure a newly installed server, or to re-configure an existing server.

MySQL Documentation: This is a link to the MySQL server documentation that is stored locally in the MySQL server installation directory. This option is not available when the MySQL server is installed from the essential installation package.