mysqld is not running on the local host. Check your operating system's process list to ensure the mysqld process is present.

You're running a MySQL server on Windows with many TCP/IP connections to it. If you're experiencing that quite often your clients get that error, you can find a workaround here: Section B.1.2.2.1, “Connection to MySQL Server Failing on Windows”.

You are running on a system that uses MIT-pthreads. If you are running on a system that doesn't have native threads, mysqld uses the MIT-pthreads package. See Section 2.1.1, “Operating Systems Supported by MySQL Community Server”. However, not all MIT-pthreads versions support Unix socket files. On a system without socket file support, you must always specify the host name explicitly when connecting to the server. Try using this command to check the connection to the server:

shell> mysqladmin -h `hostname` version

Someone has removed the Unix socket file that mysqld uses (/tmp/mysql.sock by default). For example, you might have a cron job that removes old files from the /tmp directory. You can always run mysqladmin version to check whether the Unix socket file that mysqladmin is trying to use really exists. The fix in this case is to change the cron job to not remove mysql.sock or to place the socket file somewhere else. See Section B.1.4.5, “How to Protect or Change the MySQL Unix Socket File”.

You have started the mysqld server with the --socket=/path/to/socket option, but forgotten to tell client programs the new name of the socket file. If you change the socket path name for the server, you must also notify the MySQL clients. You can do this by providing the same --socket option when you run client programs. You also need to ensure that clients have permission to access the mysql.sock file. To find out where the socket file is, you can do:

shell> netstat -ln | grep mysql

See Section B.1.4.5, “How to Protect or Change the MySQL Unix Socket File”.

You are using Linux and one server thread has died (dumped core). In this case, you must kill the other mysqld threads (for example, with kill or with the mysql_zap script) before you can restart the MySQL server. See Section B.1.4.2, “What to Do If MySQL Keeps Crashing”.

The server or client program might not have the proper access privileges for the directory that holds the Unix socket file or the socket file itself. In this case, you must either change the access privileges for the directory or socket file so that the server and clients can access them, or restart mysqld with a --socket option that specifies a socket file name in a directory where the server can create it and where client programs can access it.

Check whether the server is running on that host by executing telnet some_host 3306 and pressing the Enter key a couple of times. (3306 is the default MySQL port number. Change the value if your server is listening to a different port.) If there is a MySQL server running and listening to the port, you should get a response that includes the server's version number. If you get an error such as telnet: Unable to connect to remote host: Connection refused, then there is no server running on the given port.

If the server is running on the local host, try using mysqladmin -h localhost variables to connect using the Unix socket file. Verify the TCP/IP port number that the server is configured to listen to (it is the value of the port variable.)

If you are running under Linux and Security-Enhanced Linux (SELinux) is enabled, make sure you have disabled SELinux protection for the mysqld process.

Upgrade all client programs to use a 4.1.1 or newer client library.

When connecting to the server with a pre-4.1 client program, use an account that still has a pre-4.1-style password.

Reset the password to pre-4.1 style for each user that needs to use a pre-4.1 client program. This can be done using the SET PASSWORD statement and the OLD_PASSWORD() function:

mysql> SET PASSWORD FOR
    -> 'some_user'@'some_host' = OLD_PASSWORD('newpwd');

Alternatively, use UPDATE and FLUSH PRIVILEGES:

mysql> UPDATE mysql.user SET Password = OLD_PASSWORD('newpwd')
    -> WHERE Host = 'some_host' AND User = 'some_user';
mysql> FLUSH PRIVILEGES;

Substitute the password you want to use for “newpwd” in the preceding examples. MySQL cannot tell you what the original password was, so you'll need to pick a new one.

Tell the server to use the older password hashing algorithm:

You (or the db administrator) has killed the running thread with a KILL statement or a mysqladmin kill command.

You tried to run a query after closing the connection to the server. This indicates a logic error in the application that should be corrected.

A client application running on a different host does not have the necessary privileges to connect to the MySQL server from that host.

You got a timeout from the TCP/IP connection on the client side. This may happen if you have been using the commands: mysql_options(..., MYSQL_OPT_READ_TIMEOUT,...) or mysql_options(..., MYSQL_OPT_WRITE_TIMEOUT,...). In this case increasing the timeout may help solve the problem.

You have encountered a timeout on the server side and the automatic reconnection in the client is disabled (the reconnect flag in the MYSQL structure is equal to 0).

You are using a Windows client and the server had dropped the connection (probably because wait_timeout expired) before the command was issued.

The problem on Windows is that in some cases MySQL doesn't get an error from the OS when writing to the TCP/IP connection to the server, but instead gets the error when trying to read the answer from the connection.

Prior to MySQL 5.1.8, even if the reconnect flag in the MYSQL structure is equal to 1, MySQL does not automatically reconnect and re-issue the query as it doesn't know if the server did get the original query or not.

The solution to this is to either do a mysql_ping() on the connection if there has been a long time since the last query (this is what MyODBC does) or set wait_timeout on the mysqld server so high that it in practice never times out.

You can also get these errors if you send a query to the server that is incorrect or too large. If mysqld receives a packet that is too large or out of order, it assumes that something has gone wrong with the client and closes the connection. If you need big queries (for example, if you are working with big BLOB columns), you can increase the query limit by setting the server's max_allowed_packet variable, which has a default value of 1MB. You may also need to increase the maximum packet size on the client end. More information on setting the packet size is given in Section B.1.2.10, “Packet too large”.

An INSERT or REPLACE statement that inserts a great many rows can also cause these sorts of errors. Either one of these statements sends a single request to the server irrespective of the number of rows to be inserted; thus, you can often avoid the error by reducing the number of rows sent per INSERT or REPLACE.

You also get a lost connection if you are sending a packet 16MB or larger if your client is older than 4.0.8 and your server is 4.0.8 and above, or the other way around.

It is also possible to see this error if host name lookups fail (for example, if the DNS server on which your server or network relies goes down). This is because MySQL is dependent on the host system for name resolution, but has no way of knowing whether it is working — from MySQL's point of view the problem is indistinguishable from any other network timeout.

You may also see the MySQL server has gone away error if MySQL is started with the --skip-networking option.

Another networking issue that can cause this error occurs if the MySQL port (default 3306) is blocked by your firewall, thus preventing any connections at all to the MySQL server.

You can also encounter this error with applications that fork child processes, all of which try to use the same connection to the MySQL server. This can be avoided by using a separate connection for each child process.

You have encountered a bug where the server died while executing the query.

Indicate whether the MySQL server died. You can find information about this in the server error log. See Section B.1.4.2, “What to Do If MySQL Keeps Crashing”.

If a specific query kills mysqld and the tables involved were checked with CHECK TABLE before you ran the query, can you provide a reproducible test case? See MySQL Internals: Porting.

What is the value of the wait_timeout system variable in the MySQL server? (mysqladmin variables gives you the value of this variable.)

Have you tried to run mysqld with the general query log enabled to determine whether the problem query appears in the log? (See Section 5.2.3, “The General Query Log”.)

The client program did not call mysql_close() before exiting.

The client had been sleeping more than wait_timeout or interactive_timeout seconds without issuing any requests to the server. See Section 5.1.4, “Server System Variables”.

The client program ended abruptly in the middle of a data transfer.

A client doesn't have privileges to connect to a database.

A client uses an incorrect password.

A connection packet doesn't contain the right information.

It takes more than connect_timeout seconds to get a connect packet. See Section 5.1.4, “Server System Variables”.

Use of Ethernet protocol with Linux, both half and full duplex. Many Linux Ethernet drivers have this bug. You should test for this bug by transferring a huge file via FTP between the client and server machines. If a transfer goes in burst-pause-burst-pause mode, you are experiencing a Linux duplex syndrome. The only solution is switching the duplex mode for both your network card and hub/switch to either full duplex or to half duplex and testing the results to determine the best setting.

Some problem with the thread library that causes interrupts on reads.

Badly configured TCP/IP.

Faulty Ethernets, hubs, switches, cables, and so forth. This can be diagnosed properly only by replacing hardware.

The max_allowed_packet variable value is too small or queries require more memory than you have allocated for mysqld. See Section B.1.2.10, “Packet too large”.

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.

If you are using InnoDB tables and run out of room in the InnoDB tablespace. In this case, the solution is to extend the InnoDB tablespace. See Section 13.6.5, “Adding, Removing, or Resizing InnoDB Data and Log Files”.

You are using MyISAM tables on an operating system that supports files only up to 2GB in size and you have hit this limit for the data file or index file.

You are using a MyISAM table and the space required for the table exceeds what is allowed by the internal pointer size. MyISAM allows data and index files to grow up to 256TB by default, but this limit can be changed up to the maximum allowable size of 65,536TB (256⁷ – 1 bytes).

If you need a MyISAM table that is larger than the default limit and your operating system supports large files, the CREATE TABLE statement supports AVG_ROW_LENGTH and MAX_ROWS options. See Section 12.1.17, “CREATE TABLE Syntax”. The server uses these options to determine how large a table to allow.

If the pointer size is too small for an existing table, you can change the options with ALTER TABLE to increase a table's maximum allowable size. See Section 12.1.7, “ALTER TABLE Syntax”.

ALTER TABLE tbl_name MAX_ROWS=1000000000 AVG_ROW_LENGTH=nnn;

You have to specify AVG_ROW_LENGTH only for tables with BLOB or TEXT columns; in this case, MySQL can't optimize the space required based only on the number of rows.

To change the default size limit for MyISAM tables, set the myisam_data_pointer_size, which sets the number of bytes used for internal row pointers. The value is used to set the pointer size for new tables if you do not specify the MAX_ROWS option. The value of myisam_data_pointer_size can be from 2 to 7. A value of 4 allows tables up to 4GB; a value of 6 allows tables up to 256TB.

You can check the maximum data and index sizes by using this statement:

SHOW TABLE STATUS FROM db_name LIKE 'tbl_name';

You also can use myisamchk -dv /path/to/table-index-file. See Section 12.5.5, “SHOW Syntax”, or Section 4.6.3, “myisamchk — MyISAM Table-Maintenance Utility”.

Other ways to work around file-size limits for MyISAM tables are as follows:

You are using the NDB storage engine, in which case you need to increase the values for the DataMemory and IndexMemory configuration parameters in your config.ini file. See MySQL Cluster Data Node Configuration Parameters.

You are using the MEMORY (HEAP) storage engine; in this case you need to increase the value of the max_heap_table_size system variable. See Section 5.1.4, “Server System Variables”.

You may be running a new version of mysqld with an old user table. You can check this by executing mysqlshow mysql user to see whether the Password column is shorter than 16 characters. If so, you can correct this condition by running the scripts/add_long_password script.

The account has an old password (eight characters long). Update the account in the user table to have a new password.

You have specified a password in the user table without using the PASSWORD() function. Use mysql to update the account in the user table with a new password, making sure to use the PASSWORD() function:

mysql> UPDATE user SET Password=PASSWORD('newpwd')
    -> WHERE User='some_user' AND Host='some_host';

Because MySQL uses directories and files to store databases and tables, database and table names are case sensitive if they are located on a file system that has case-sensitive file names.

Even for file systems that are not case sensitive, such as on Windows, all references to a given table within a query must use the same lettercase.

The character set is a multi-byte character set and you have no support for the character set in the client. In this case, you need to recompile the client by running configure with the --with-charset=charset_name or --with-extra-charsets=charset_name option. See Section 2.10.2, “Typical configure Options”.

All standard MySQL binaries are compiled with --with-extra-charsets=complex, which enables support for all multi-byte character sets. See Section 9.2, “The Character Set Used for Data and Sorting”.

The character set is a simple character set that is not compiled into mysqld, and the character set definition files are not in the place where the client expects to find them.

In this case, you need to use one of the following methods to solve the problem:

Add the path to the directory where libmysqlclient.so is located to the LD_LIBRARY_PATH environment variable.

Add the path to the directory where libmysqlclient.so is located to the LD_LIBRARY environment variable.

Copy libmysqlclient.so to some directory that is searched by your system, such as /lib, and update the shared library information by executing ldconfig.

The MySQL server or the server host was killed in the middle of an update.

You have found a bug in mysqld that caused it to die in the middle of an update.

Some external program is manipulating data files or index files at the same time as mysqld without locking the table properly.

You are running many mysqld servers using the same data directory on a system that doesn't support good file system locks (normally handled by the lockd lock manager), or you are running multiple servers with external locking disabled.

You have a crashed data file or index file that contains very corrupt data that confused mysqld.

You have found a bug in the data storage code. This isn't likely, but it is at least possible. In this case, you can try to change the storage engine to another engine by using ALTER TABLE on a repaired copy of the table.

Stop the mysqld server with mysqladmin shutdown, run myisamchk --silent --force */*.MYI from the data directory to check all MyISAM tables, and restart mysqld. This ensures that you are running from a clean state. See Chapter 5, MySQL Server Administration.

Start mysqld with the general query log enabled (see Section 5.2.3, “The General Query Log”). Then try to determine from the information written to the log whether some specific query kills the server. About 95% of all bugs are related to a particular query. Normally, this is one of the last queries in the log file just before the server restarts. See Section 5.2.3, “The General Query Log”. If you can repeatedly kill MySQL with a specific query, even when you have checked all tables just before issuing it, then you have been able to locate the bug and should submit a bug report for it. See Section 1.6, “How to Report Bugs or Problems”.

Try to make a test case that we can use to repeat the problem. See MySQL Internals: Porting.

Try running the tests in the mysql-test directory and the MySQL benchmarks. See Section 21.1.2, “MySQL Test Suite”. They should test MySQL rather well. You can also add code to the benchmarks that simulates your application. The benchmarks can be found in the sql-bench directory in a source distribution or, for a binary distribution, in the sql-bench directory under your MySQL installation directory.

Try the fork_big.pl script. (It is located in the tests directory of source distributions.)

If you configure MySQL for debugging, it is much easier to gather information about possible errors if something goes wrong. Configuring MySQL for debugging causes a safe memory allocator to be included that can find some errors. It also provides a lot of output about what is happening. Reconfigure MySQL with the --with-debug or --with-debug=full option to configure and then recompile. See MySQL Internals: Porting.

Make sure that you have applied the latest patches for your operating system.

Use the --skip-external-locking option to mysqld. On some systems, the lockd lock manager does not work properly; the --skip-external-locking option tells mysqld not to use external locking. (This means that you cannot run two mysqld servers on the same data directory and that you must be careful if you use myisamchk. Nevertheless, it may be instructive to try the option as a test.)

Have you tried mysqladmin -u root processlist when mysqld appears to be running but not responding? Sometimes mysqld is not comatose even though you might think so. The problem may be that all connections are in use, or there may be some internal lock problem. mysqladmin -u root processlist usually is able to make a connection even in these cases, and can provide useful information about the current number of connections and their status.

Run the command mysqladmin -i 5 status or mysqladmin -i 5 -r status in a separate window to produce statistics while you run your other queries.

Try the following:

Try to simulate your application with a Perl script to force MySQL to crash or misbehave.

Send a normal bug report. See Section 1.6, “How to Report Bugs or Problems”. Be even more detailed than usual. Because MySQL works for many people, it may be that the crash results from something that exists only on your computer (for example, an error that is related to your particular system libraries).

If you have a problem with tables containing dynamic-length rows and you are using only VARCHAR columns (not BLOB or TEXT columns), you can try to change all VARCHAR to CHAR with ALTER TABLE. This forces MySQL to use fixed-size rows. Fixed-size rows take a little extra space, but are much more tolerant to corruption.

The current dynamic row code has been in use for several years with very few problems, but dynamic-length rows are by nature more prone to errors, so it may be a good idea to try this strategy to see whether it helps.

Do not rule out your server hardware when diagnosing problems. Defective hardware can be the cause of data corruption. Particular attention should be paid to your memory and disk subsystems when troubleshooting hardware.

It checks once every minute to see whether there is enough space to write the current row. If there is enough space, it continues as if nothing had happened.

Every 10 minutes it writes an entry to the log file, warning about the disk-full condition.

To continue, you only have to free enough disk space to insert all records.

To abort the thread, you must use mysqladmin kill. The thread is aborted the next time it checks the disk (in one minute).

Other threads might be waiting for the table that caused the disk-full condition. If you have several “locked” threads, killing the one thread that is waiting on the disk-full condition allows the other threads to continue.

Specify the path in a global or local option file. For example, put the following lines in /etc/my.cnf:

[mysqld]
socket=/path/to/socket

[client]
socket=/path/to/socket

See Section 4.2.3.3, “Using Option Files”.

Specify a --socket option on the command line to mysqld_safe and when you run client programs.

Set the MYSQL_UNIX_PORT environment variable to the path of the Unix socket file.

Recompile MySQL from source to use a different default Unix socket file location. Define the path to the file with the --with-unix-socket-path option when you run configure. See Section 2.10.2, “Typical configure Options”.

When you compare two columns

When you compare a DATE, TIME, DATETIME, or TIMESTAMP column to an expression

When you use any other comparison method than those just listed, such as IN or STRCMP().

Create a new table named A-xxx with the requested structural changes.

Copy all rows from the original table to A-xxx.

Rename the original table to B-xxx.

Rename A-xxx to your original table name.

Delete B-xxx.

A TEMPORARY table can only be of type MEMORY, MyISAM, MERGE, or InnoDB.

Temporary tables are not supported for MySQL Cluster.

You cannot refer to a TEMPORARY table more than once in the same query. For example, the following does not work:

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

This error also occurs if you refer to a temporary table multiple times in a stored function under different aliases, even if the references occur in different statements within the function.

The SHOW TABLES statement does not list TEMPORARY tables.

You cannot use RENAME to rename a TEMPORARY table. However, you can use ALTER TABLE instead:

mysql> ALTER TABLE orig_name RENAME new_name;

There are known issues in using temporary tables with replication. See Section 16.3.1, “Replication Features and Issues”, for more information.

Bug#40552: Race condition around default_directories in load_defaults()

Bug#47007: Unresolved reference to 'innodb_system_libs' in "mysql_config"

Bug#43560: client crashes in mysql_stmt_execute/mysql_stmt_close after connection loss

Bug#45017: Failure to connect if hostname maps to multiple addresses

Bug#42675: Dangling pointer leads to a client crash (mysys/my_error.c patch enclosed)

Bug#44278: mysqlhotcopy unable to backup schema with a hyphen in its name

Bug#35934: mysql_upgrade calls mysqlcheck with insufficient parameters

Bug#34129: mysqldumpslow does not aggregate times

Bug#39852: bug in mysql_setpermission

Bug#40395: mysqladmin -i delay extended-status does not iterate with -r

Bug#34861: mysqldump with --tab gives weird output for triggers.

Bug#46310: mysql not handling <BACKSPACE> properly with multi-byte chars

Bug#46776: MySQL client confused by quotes, treats data as commands

Bug#45740: mysqldump doesn't dump general_log and slow_query causes restore problem

Bug#36391: mysqlbinlog creates invalid charset statements

Bug#30946: mysqldump silently ignores --default-character-set when used with --tab

Bug#42640: mysqld crashes when unsafe statements are executed (STRICT_TRANS_TABLES mode)

Bug#42610: Dynamic plugin broken in 5.1.31

Bug#41078: With CURSOR_TYPE_READ_ONLY mysql_stmt_fetch() returns short string value.

Bug#46486: warnings produced when running mysql_install_db

Bug#39494: please support >4GB key_buffer_size on windows

Bug#38883: thd_security_context is not thread safe, crashes?

Bug#38941: fast mutexes in MySQL 5.1 have mutex contention when calling random()

Bug#40230: 23 seconds difference while the time_zone is SYSTEM

Bug#42144: plugin_load fails on PPC64

Bug#31616: div_precision_increment description looks wrong

Bug#43354: Use key hint can crash server in explain extended query

Bug#22891: session level max_allowed_packet can be set but is ignored

Bug#40949: Debug version of MySQL server crashes when run OPTIMIZE on compressed table.

Bug#46815: CONCAT_WS returning wrong data

Bug#46539: Various crashes on INSERT IGNORE SELECT + SELECT FOR UPDATE

Bug#43435: LOCK_open does not use MY_MUTEX_INIT_FAST

Bug#45336: --enable-foobar doesn't work for any plugin foobar.

Bug#35068: Assertion fails when reading from i_s.tables and there is incorrect merge table

Bug#46043: mysqld --skip-innodb does not skip InnoDB

Bug#40877: multi statement execution fails in 5.1.30

Bug#45058: init_available_charsets uses double checked locking

Bug#46804: innodb test fails on PB-2 with a crash

Bug#46941: crash with lower_case_table_names=2 and foreign key data dictionary confusion

Bug#45638: Create temporary table with engine innodb fails

Bug#42503: "Lost connection" errors when using compression protocol

Bug#40757: server crash after failed plugin/engine initialization

Bug#40536: SELECT is blocked by INSERT DELAYED waiting on upgrading lock, even with low_pri

Bug#43827: Server closes connections and restarts

Bug#46760: Fast ALTER TABLE no longer works for InnoDB

Bug#41030: Wrong meta data (incorrect fieldlen)

Bug#42563: Message tells me to repair table though Storage Engine doesn't allow me to.

Bug#44521: Prepared Statement: CALL p() - crashes: `! thd->main_da.is_sent' failed et.al.

Bug#46893: Performance degradation on SuSE-10/RHEL in dbt2 test

Bug#47012: archive tables are not upgradeable, server crashes on access

Bug#37719: Crash if rename Archive table to same name with different case and then select

Bug#29203: archive tables have weird values in show table status

Bug#46961: archive engine loses rows during self joining select!

Bug#46565: repair of partition fail for archive engine

Bug#32880: Repairing Archive table fails with internal error 144

Bug#41441: repair csv table crashes debug server

Bug#33094: Error in upgrading from 5.0 to 5.1 when table contains triggers

Bug#41385: Crash when attempting to repair a #mysql50# upgraded table with triggers.

Bug#40053: 'check table .. for upgrade' doesn't detect collation change made in 5.1.24-rc

Bug#32831: libmysql should be built with all charsets

Bug#43207: wrong LC_TIME names for romanian locale

Bug#46448: trailing spaces are not ignored when user collation maps space != 0x20

Bug#45012: my_like_range_cp932 generates invalid string

Bug#43593: dump/backup/restore/upgrade tools fails

Bug#45485: replication different between master/slaver using procedure with gbk

Bug#45645: Mysql server close all connection and restart using lower function

Bug#41084: full-text index added to custom UCA collation not working

Bug#42524: Function pthread_setschedprio() is defined but seems broken on i5/OS PASE

Bug#26760: SSL support missing from 5.1.15-0 x86_64 Client Programs?

Bug#43715: Link errors when trying to link mysql_embedded.exe

Bug#43449: Undefined symbol __1cG__CrunMex_rethrow_q6F_v_ when compiling using Sun Studio

Bug#42872: In MySQL 5.1.31, unrecognized --with-innodb, --with-partition, --with-federated

Bug#39996: 5.1 fails to compile on Windows 32-bit with VS2005

Bug#45706: rpm install fails due to incorrect libc linking

Bug#46309: MySQL 5.1.36 fails to compile using ICC 11.1

Bug#45113: mysql_config returns incorrect path if built with prefix != execprefix

Bug#42599: error: `pthread_setschedprio' was not declared in this scope

Bug#25404: mysql_config need several issues corrected

Bug#38364: gen_lex_hash segmentation fault in debug build

Bug#47337: innochecksum not built for --with-plugin-innodb_plugin --without-plugin-innobase

Bug#42733: type-punning warnings when compiling MySQL with -O2/-O3 -Wall and gcc 4.x

Bug#39102: valgrind build does not compile in realpath, which make DATA/INDEX DIR fail

Bug#31506: detection of function's availability is wrong in configure.in

Bug#38697: utf8_general_cs cannot be used with Windows?

Bug#40862: main.subselect_notembedded test case fails

Bug#46980: Option "--without-server" still not working in 5.1

Bug#40700: aclocal warnings for missing cache-id's

Bug#42071: Obsoleted configure options were still used in the official compiling.

Bug#39571: abi_check: Does not create all prerequisites

Bug#42141: Compiler crash in "mf_format.c" when optimizing for 64 bit

Bug#42721: configure.in invokes 'nm' directly

Bug#39288: MySQL Embedded server (libmysqld.a) is built without -fPIC flag

Bug#42386: MySQL .msi installer does not start configuration wizard on Vista when prompted

Bug#37294: Windows .msi - 'Repair' option doesn't back out as expected

Bug#46146: Configuration wizard fails if the service already exists

Bug#44428: Cannot recreate instance after clean install (apply security settings fails)

Bug#38723: MySQL Configuration Wizard on Vista unreadable

Bug#45196: Some collations do not sort correctly with IBMDB2I

Bug#45983: ibmdb2i_create_index_option=1 not working for primary key

Bug#45803: Inaccurate estimates for partial key values with IBMDB2I

Bug#44022: CREATE TABLE sometimes fails silently for IBMDB2I engine

Bug#45197: cp1250 character set with IBMDB2I generates 2027 error

Bug#43343: ibmdb2i Storage Engine does not honor timezone settings with INSERT

Bug#44025: Some schema names longer than 8 characters not supported by IBMDB2I

Bug#44856: IBMDB2I gives misleading 2504 error

Bug#44811: Tests with utf8 charset fail with ibmdb2i on 64bit MySQL

Bug#44020: Unicode Swedish collations not working with IBMDB2I

Bug#46730: Tables created witn SE IBMDB2I show incorr update and create timestamps

Bug#37016: TRUNCATE TABLE removes some rows but not all

Bug#23113: Different behavior on altering ENUM fields between 5.0 and 5.1

Bug#39372: "Smart" ALTER TABLE not so smart after all.

Bug#41465: confusing error message when comment is too long

Bug#39200: optimize table does not recognize ROW_FORMAT=COMPRESSED

Bug#45567: Fast ALTER TABLE broken for enum and set

Bug#43508: Renaming timestamp or date column triggers table copy

Bug#40886: ALTER TABLE statements appear to randomly fail on Mac OS 10.4

Bug#40277: SHOW CREATE VIEW returns invalid SQL

Bug#46766: ALTER TABLE corrupts table on combined drop and add index

Bug#35796: SHOW CREATE TABLE and default value for BIT field

Bug#41041: Obsolete debug code can be used to crash server

Bug#39920: MySQL cannot deal with Leap Second expression in string literal.

Bug#44743: Join in combination with concat does not always work

Bug#41156: List of derived tables acts like a chain of mutually-nested subqueries

Bug#40384: Gap in auto_increment sequence when inserts fire a trigger

Bug#45168: assertion with convert() and empty set value

Bug#33717: INSERT...(default) fails for enum. Crashes CSV tables, loads spaces for MyISAM

Bug#38693: leaked memory with blobs!

Bug#46259: 5.0.83 -> 5.1.36, query doesn't work

Bug#44306: Assertion fail on duplicate key error in 'INSERT ... SELECT' statements

Bug#33844: Server crashes when client dies during LOAD DATA INFILE

Bug#40745: Error during WHERE clause calculation in UPDATE leads to an assertion failure

Bug#45962: memory leak after 'sort aborted' errors

Bug#43385: Cannot ALTER DATABASE ... UPGRADE DATA DIRECTORY NAME when Views exist

Bug#40127: Multiple table DELETE IGNORE hangs on foreign key constraint violation on 5.0

Bug#44399: crash with statement using TEXT columns, aggregates, GROUP BY, and HAVING

Bug#47097: ALTER <existing table> ENGINE = MERGE/BLACKHOLE ... is allowed + data loss

Bug#47047: incorrect return type length

Bug#42364: SHOW ERRORS returns empty resultset after dropping non existent table

Bug#41121: "Statement is not safe to log in statement format" is prints table name only

Bug#41077: Warning contains wrong future version

Bug#46265: Can not disable warning about unsafe statements for binary logging

Bug#39746: Debug flag breaks struct definition (server crash)

Bug#28234: global/session scope - documentation vs implementation

Bug#42907: Multi-term boolean fulltext query containing a single quote fails in 5.1.x

Bug#39640: ftb_query_add_word does not recognice MYSQL_FTFLAGS_NEED_COPY

Bug#31435: ha_innodb.cc:3983: ulint convert_search_mode_to_innobase(ha_rkey_function): Asse

Bug#35570: CHECKSUM TABLE unreliable if LINESTRING field (same content / differen checksum)

Bug#43748: crash when non-super user tries to kill the replication threads

Bug#41456: SET PASSWORD hates CURRENT_USER()

Bug#41363: crash of mysqld on windows with aggregate in case

Bug#40104: regression with table names?

Bug#37284: Crash in Field_string::type()

Bug#41710: MySQL 5.1.30 crashes on the latest OpenSolaris 10

Bug#30261: "mysqld --help" no longer possible for root

Bug#38477: my_pthread_setprio can change dispatch class on Solaris, not just priority

Bug#44367: valgrind warnings with find_in_set() functions

Bug#38249: innodb_log_arch_dir still in support files

Bug#45309: InnoDB does not rollback for delete and update queries if query was killed

Bug#44664: valgrind warning for COMMIT_AND_CHAIN and ROLLBACK_AND_CHAIN

Bug#39265: SQL_MODE OLD_NOT_NULL_CHECK_BEHAVIOUR for backward compatibility

Bug#43962: "Packets out of order" calling a SHOW TABLE STATUS

Bug#10206: InnoDB: Transaction requiring Max_BinLog_Cache_size > 4GB always rollsback.

Bug#47130: misplaced or redundant check for null pointer ?

Bug#42158: leak: SSL_get_peer_certificate() doesn't have matching X509_free()

Bug#36751: Segmentation fault in ctype-bin.c:308; Linux 86_64, with-max-indexes=128

Bug#45548: XA transaction without access to InnoDB tables crashes the server

Bug#42957: no results from select where .. (col=col and col=col) or ... (false expression)

Bug#44358: valgrind errors with decode() function

Bug#40915: Events takes mutex in wrong order which can easily lead to deadlocks

Bug#44736: mysqld_safe's my_which() is broken and doesn't find 'logger'

Bug#44638: mysql_upgrade, mysqlcheck output instance unclear

Bug#43606: 4GB Limit on huge_pages shared memory set-up

Bug#44365: valgrind warnings with encrypt() function

Bug#42146: DATETIME fractional seconds parse error

Bug#39178: Server crash in YaSSL with non-RSA-requesting client if server uses RSA key

Bug#44164: TL_WRITE has no description in lock_descriptions[]

Bug#40657: assertion with out of range variables and traditional sql_mode

Bug#46261: Plugins can be installed with --skip-grant-tables

Bug#41612: resolve_stack_dump does not decode 5.1 stack trace

Bug#34043: Server loops excessively in _checkchunk() when safemalloc is enabled

Bug#39541: CHECK TABLE on information_schema myisam tables produces error

Bug#39955: SELECT on INFORMATION_SCHEMA.GLOBAL_VARIABLES takes too long

Bug#35275: INFORMATION_SCHEMA.TABLES.CREATE_OPTIONS omits KEY_BLOCK_SIZE

Bug#38918: selecting from information_schema.columns is disproportionately slow

Bug#42758: INFORMATION_SCHEMA.COLUMNS is inconsistent

Bug#38909: CREATE_OPTIONS in information_schema produces wrong results

Bug#35789: wrong datatypes for collation and charset columns in EVENTS, ROUTINES, TRIGGERS

Bug#45357: 5.1.35 crashes with Failing assertion: index->type & DICT_CLUSTERED

Bug#39320: assert btr/btr0pcur.c line 217 -innodb_locks_unsafe_for_binlog or read committed

Bug#40386: Not flushing query cache after truncate

Bug#40360: Binlog related errors with binlog off

Bug#42400: InnoDB autoinc code can't handle floating-point columns

Bug#42101: Race condition in innodb_commit_concurrency

Bug#21704: Renaming column does not update FK definition

Bug#45097: Hang during recovery, redo logs for doublewrite buffer pages

Bug#42152: Race condition in lock_is_table_exclusive()

Bug#38231: Innodb crash in lock_reset_all_on_table() on TRUNCATE + LOCK / UNLOCK

Bug#38189: innodb_stats_on_metadata missing

Bug#47233: Innodb calls push_warning(MYSQL_ERROR::WARN_LEVEL_ERROR)

Bug#44030: Error: (1500) Couldn't read the MAX(ID) autoinc value from the index (PRIMARY)

Bug#36411: "Failed to read auto-increment value from storage engine" in 5.1.24 auto-inc

Bug#43203: Overflow from auto incrementing causes server segv

Bug#42075: dict_load_indexes failure in dict_load_table will corrupt the dictionary cache

Bug#39793: Foreign keys not constructed when column has a '#' in a comment or default value

Bug#43660: SHOW INDEXES/ANALYZE does NOT update cardinality for indexes of InnoDB table

Bug#39648: Replication failure on RBR + Innodb + 2 bit fields + LIMIT + no PK

Bug#37885: row_search_for_mysql may gap lock unnecessarily with SQL comments in query

Bug#39438: Testcase for Bug#39436 crashes on 5.1 in fil_space_get_latch

Bug#36169: create innodb compressed table with too large row size crashed

Bug#44320: InnoDB: missing DB_ROLL_PTR in Table Monitor COLUMNS output

Bug#39830: Table autoinc value not updated on first insert

Bug#45749: Race condition in SET GLOBAL innodb_commit_concurrency=DEFAULT

Bug#42383: main.innodb_bug39438: Can't create table 'test.bug39438'

Bug#40369: dtype_get_sql_null_size() returns 0 or 1, not the size

Bug#42279: Race condition in btr_search_drop_page_hash_when_freed()

Bug#46256: drop table with unknown collation crashes innodb

Bug#35498: Cannot get table test/table1 auto-inccounter value in ::info

Bug#46193: crash when accessing tables after enabling innodb_force_recovery option

Bug#41671: Semi-consistent read does not unlock rows in READ COMMITTED mode

Bug#42714: AUTO_INCREMENT errors in 5.1.31

Bug#32430: 'show innodb status' causes errors Invalid (old?) table or database name in logs

Bug#46718: InnoDB plugin incompatible with gcc 4.1 (at least: on PPC): "Undefined symbol"

Bug#37788: InnoDB Plugin: AUTO_INCREMENT wrong for compressed tables

Bug#45418: 'MySQL Server 5.1 Setup Wizard ended prematurely' message during .msi install

Bug#17270: mysql client tool could not find ../share/charsets folder and fails.

Bug#46258: Windows Install zaps prev. instance, even though basedir is different

Bug#41828: mysql_install_db misses mysqld options when using --basedir

Bug#41313: network administrator does not have TRIGGER and EVENT privileges

Bug#44073: 'could not start service' message but service starts anyway!

Bug#41348: INSERT INTO tbl SELECT * FROM temp_tbl overwrites locking type of temp table

Bug#46944: Internal prepared XA transction XIDs are not removed if server_id changes

Bug#44672: Assertion failed: thd->transaction.xid_state.xid.is_null()

Bug#41110: crash with handler command when used concurrently with alter table

Bug#39843: DELETE requires write access to table in subquery in where clause

Bug#33278: ANALYZE TABLE in InnoDB holds exclusive locks on subsequent execution

Bug#43885: main.variables-big fails because of warnings within the server log

Bug#37132: Logging to slow_log table fails with very slow queries

Bug#29751: renaming server logs at FLUSH LOGS

Bug#40281: partitioning the general log table crashes the server

Bug#39886: Table full for MEMORY table is not written into error log

Bug#40675: MySQL 5.1 crash with index merge algorithm and Merge tables

Bug#45796: invalid memory reads and writes when altering merge and base tables

Bug#41305: server crashes when inserting duplicate row into a merge table

Bug#45800: crash when replacing into a merge table and there is a duplicate

Bug#44040: MySQL allows creating a MERGE table upon VIEWs but crashes when using it

Bug#41212: crash after race condition between merge table and table_cache evictions

Bug#41574: REPAIR TABLE: crashes for compressed tables

Bug#40321: ha_myisam::info could update rec_per_key incorrectly

Bug#40634: table scan temporary table is 4x slower due to mmap instead instead of caching

Bug#35111: Truncate a MyISAM partitioned table does not reset the auto_increment value.

Bug#38848: myisam_use_mmap causes widespread myisam corruption on windows

Bug#37756: enabling fulltext indexes with myisam_repair_threads > 1 causes crash

Bug#47073: valgrind errs, corruption,failed repair of partition,low myisam_sort_buffer_size

Bug#37631: Incorrect key file for table after upgrading from 5.0 to 5.1

Bug#40827: Killing insert-select to MyISAM can cause table corruption

Bug#43940: 64-bit windows myisamchk doesn't support key_buffer_size > 4G

Bug#46454: MySQL wrong index optimisation leads to incorrect result & crashes

Bug#37362: Crash in do_field_eq

Bug#34773: query with explain extended and derived table / other table crashes server

Bug#38842: Fix for 25951 seems incorrect

Bug#45828: Optimizer won't use partial primary key if another index can prevent filesort

Bug#37742: HA_EXTRA_KEYREAD flag is set when key contains only prefix of requested column

Bug#46003: Valgrind warning in JOIN::init()

Bug#46159: simple query that never returns

Bug#47150: Assertion in Field_long::val_int() on MERGE + TRIGGER + multi-table UPDATE

Bug#37948: Assertion in Field_long::val_int

Bug#43029: FORCE INDEX FOR ORDER BY is ignored when join buffering is used

Bug#37936: ASSERT_COLUMN_MARKED_FOR_WRITE in Field_datetime::store , Field_varstring::store

Bug#41543: Assertion `m_status == DA_ERROR' failed in Diagnostics_area::sql_errno

Bug#44886: SIGSEGV in test_if_skip_sort_order() - uninitialized variable used as subscript

Bug#37822: Correlated subquery with IN and IS UNKNOWN provides wrong result

Bug#46607: Assertion failed: (cond_type == Item::FUNC_ITEM) results in server crash

Bug#46051: Selects with a subquery sporadically return wrong data

Bug#46629: Item_in_subselect::val_int(): Assertion `0' on subquery inside a SP

Bug#31399: Wrong query result when doing join buffering over BIT fields

Bug#39433: poor optimized query

Bug#43835: SHOW VARIABLES does not include 0 for slave_skip_errors

Bug#20415: Output of mysqld --help --verbose is incomplete

Bug#46834: Test suite missing from RPMs

Bug#43153: Version comment is too long

Bug#40845: Win inst shows screens with wrong naming "MySQL Monitoring and Advisory Service"

Bug#41838: shared-compat packages missing for Enterprise 5.1 builds

Bug#34025: mysql_config is not returning -ldl lib flag needed when using embedded server

Bug#39074: Binaries do not work on Solaris 10 older than U5

Bug#43918: Generated version string is too long for the binlog

Bug#44496: No "MySQL Manual" in Install-Package

Bug#45415: rpm upgrade recreates test database

Bug#39641: mysql_config --plugindir links to /usr/local/mysql/lib/plugin in tar.gz packages

Bug#41577: improper value in example config file

Bug#44353: build-v9.bat is missing in source archive

Bug#31143: mysqlslap.exe (and other) missing in windows install packages

Bug#41189: No debug symbols in 5.1.30 build for Mac OSX (mysql-5.1.30-osx10.5-x86.dmg)

Bug#37697: make_binary_distribution places files in wrong path

Bug#39559: dump of stored procedures / functions with C-style comment can't be read back

Bug#43746: YACC return wrong query string when parse 'load data infile' sql statement

Bug#39434: ALTER TABLE CHECK/OPTIMIZE/ANALYZE PARTITION work on non-partitioned table

Bug#14326: No formatting of SHOW CREATE TABLE output

Bug#40176: Combination of event, trigger and partitioning breaks auto increment

Bug#40954: Crash in MyISAM index code with concurrency test using partitioned tables

Bug#37721: ORDER BY when WHERE contains non-partitioned index column

Bug#40494: MYSQL server crashes on range access with partitioning and order by

Bug#45823: Assertion failure in file row/row0mysql.c line 1386

Bug#40515: Query on a partitioned table does not return 'lock wait timeout exceeded'

Bug#44821: select distinct on partitioned table returns wrong results

Bug#44653: Server crash noticed when executing random queries with partitions.

Bug#36001: Partitions: spelling and using some error messages

Bug#46354: Crash in partition_info::check_partition_info on inconsistent subpartitions

Bug#30102: Failed RENAME of partitioned table corrupts table files

Bug#45840: read_buffer_size allocated for each partition when "insert into.. select * from"

Bug#46362: Endpoint should be set to false for TO_DAYS(DATE)

Bug#20577: Partitions: use of to_days() function leads to selection failures

Bug#45807: crash accessing partitioned table and sql_mode contains ONLY_FULL_GROUP_BY

Bug#42944: partition not pruned correctly

Bug#38719: Partitioning returns a different error code for a duplicate key error

Bug#46922: crash when adding partitions and open_files_limit is reached

Bug#39893: Crash if select on a partitioned table, when partitioning is disabled

Bug#40972: Partition pruning can lead to crash for bad dates

Bug#44059: Incorrect cardinality of indexes on a partitioned table

Bug#45961: DDL on partitioned innodb tables leaves data dictionary in an inconsistent state

Bug#40389: REORGANIZE PARTITION crashes when only using one partition

Bug#46639: 1030 (HY000): Got error 124 from storage engine on INSERT ... SELECT ...

Bug#47029: Server crash when reorganizing two partitions into one with same name as the 2nd

Bug#46923: select count(*) from partitioned table fails with ONLY_FULL_GROUP_BY

Bug#46483: drop table of partitioned table may leave extraneous file

Bug#35845: unneccesary call to ha_start_bulk_insert for not used partitions

Bug#37453: Dropping/creating index on partitioned table with InnoDB Plugin locks table

Bug#36312: InnoDB DATA_FREE BUG?

Bug#39084: Getting intermittent errors with statement-based binary logging

Bug#45816: assertion failure with index containing DOUBLE column on partitioned table

Bug#46478: timestamp field incorrectly defaulted when partition is reorganized

Bug#37191: Failed assertion in CREATE VIEW

Bug#46960: Users can obtain unauthorized information about objects through SHOW CREATE VIEW

Bug#30305: Create routine in wrong context in SHOW PRIVILEGES

Bug#45100: Incomplete DROP USER in case of SQL_MODE = 'PAD_CHAR_TO_FULL_LENGTH'

Bug#43758: Query cache can lock up threads in 'freeing items' state

Bug#43861: main.query_cache_28249 fails sporadically

Bug#41098: Query Cache returns wrong result with concurrent insert

Bug#42977: RBR logs for rows with more than 250 column results in corrupt binlog.

Bug#41986: Replication slave does not pick up proper AUTO_INCREMENT value for Innodb tables

Bug#40221: Replication failure on RBR + UPDATE the primary key

Bug#40004: Replication failure with no PK + no indexes

Bug#46640: output from mysqlbinlog command in 5.1 breaks replication

Bug#39701: Mixed binlog format does not switch to row mode on LOAD_FILE

Bug#31502: 5.1.20 -> 5.1.22 Slave crashes if it gets an event w/ data for non-exist column

Bug#38230: Differences between master and slave after UPDATE or DELETE with LIMIT with pk

Bug#42941: --database paramater to mysqlbinlog fails with RBR

Bug#39753: Replication failure on MIXED + bit + myisam + no PK

Bug#45999: row based replication fails when auto_increment field = 0

Bug#42914: non-updated blob columns are included in RBR binlog record.

Bug#45243: crash on win in sql thread clear_tables_to_lock() -> free()

Bug#42749: infinite loop writing to row based binlog - processlist shows "freeing items"

Bug#44581: Slave stops when transaction with non-transactional table gets lock wait timeout

Bug#40116: Uncommited changes are replicated and stay on slave after rollback on master

Bug#45827: Stmt using two autoinc values does not produce unsafe warning

Bug#28976: Mixing trans and non-trans tables in one transaction results in incorrect binlog

Bug#40482: server/mysqlbinlog crashes when reading invalid Incident_log_event

Bug#43579: mysql_upgrade tries to alter log tables on replicated database

Bug#42851: Spurious "Statement is not safe to log in statement format." warnings

Bug#46030: rpl_truncate_3innodb causes server crash on windows

Bug#41980: SBL, INSERT .. SELECT .. LIMIT = ERROR, even when @@SQL_LOG_BIN is 0 !

Bug#40796: Crash due to heap corruption in rpl.rpl_extraColmaster_myisam

Bug#38240: Crash in safe_mutex_lock () thr_mutex.c line 97 on rotate_relay_log ()

Bug#34739: unexpected binlog file name when --log-bin is set to a directory name

Bug#38174: secure-file-priv breaks LOAD DATA INFILE replication in statement mode

Bug#46129: Failing mixed stm (with trans and non-trans tables) causes wrong seq in binlog

Bug#35583: mysqlbinlog replay fails with ERROR 1146 when temp tables are used

Bug#47160: rpl_binlog_max_cache_size fails sporadically on PB2

Bug#40013: mixed replication: row based format could lead to stale tmp tables on the slave

Bug#44179: reset slave crashes in my_error when reset_logs returns non-zero

Bug#45825: INSERT DELAYED is not unsafe: logged in statement format

Bug#36763: TRUNCATE TABLE fails to replicate when stmt-based binlogging is not supported.

Bug#45694: Deadlock in replicated statement is not retried

Bug#34628: LOAD DATA CONCURRENT INFILE drops CONCURRENT in binary log

Bug#38934: slave slave until does not work with --replicate-same-server-id

Bug#41948: Query_log_event constructor needlessly contorted

Bug#43046: mixed mode switch to row format with temp table lead to wrong result

Bug#34541: mysqlbinlog prints 'set;' in stm mode after changing autocommit mode

Bug#39526: sql_mode not retained in binary log for CREATE PROCEDURE

Bug#31240: load data infile replication between (4.0 or 4.1) and 5.1 fails

Bug#38205: Row-based Replication (RBR) causes inconsistencies: HA_ERR_FOUND_DUPP_KEY

Bug#47323: mysqlbinlog --verbose displays bad output when events contain subset of columns

Bug#44041: ALTER DATABASE change default COLLATION for following stmts of other DB on slave

Bug#44442: Incident events are silent in mysqlbinlog output

Bug#22504: load data infile sql statement in replication architechure get error

Bug#45677: Slave stops with Duplicate entry for key PRIMARY when using trigger

Bug#46130: Slave does not correctly handle "expected errors"

Bug#45242: crash on win in mysql_close() -> free()

Bug#42861: Assigning invalid directories to --slave-load-tmpdir crashes the slave

Bug#42829: binlogging enabled for all schemas regardless of binlog-db-db / binlog-ignore-db

Bug#41166: stored function requires "deterministic" if binlog_format is "statement"

Bug#39393: slave-skip-errors does not work when using ROW based replication

Bug#44270: RESET SLAVE does not reset Last_IO_Error or Last_IO_Errno

Bug#44331: Restore of database with events produces warning in replication

Bug#42415: UPDATE with LIMIT clause unsafe for statement format even when ORDER BY PK

Bug#32228: A disk full makes binary log corrupt.

Bug#41961: Some log_event types do not skip post-header when reading

Bug#45214: get_master_version_and_clock does not report error when queries fail

Bug#46014: rpl_stm_reset_slave crashes the server sporadically in pb2

Bug#38197: Errors in @@init_slave not visible in 'show slave status'

Bug#39053: UNISTALL PLUGIN does not allow the storage engine to cleanup open connections

Bug#42188: crash and/or memory corruption with user variables in trigger

Bug#38066: Events log 'note' level messages by default in the error log

Bug#40770: Server Crash when running with triggers including variable settings (rpl_sys)

Bug#45261: Crash, stored procedure + decimal

Bug#43884: SP + filename param as TEXT + LOAD_FILE inside, causes valgrind warnings in PB

Bug#41726: upgrade from 5.0 to 5.1.30 crashes if you didn't run mysql_upgrade

Bug#43587: Putting event_scheduler=1 in init SQL file crashes mysqld

Bug#36540: CREATE EVENT and ALTER EVENT statements fail with large server_id

Bug#45235: 5.1 does not support 5.0-only syntax triggers in any way

Bug#42014: Crash, name_const with collate

Bug#35558: Wrong server metadata blows up the client

Bug#45262: Bad effects with CREATE TABLE and DECIMAL

Bug#43668: Server returns wrong MAX() value with year(2) type and no index

Bug#46616: Assertion `!table->auto_increment_field_not_null' on view manipulations

Bug#40825: Error 1356 while selecting from a view with a "HAVING" clause though query works

Bug#43183: ExctractValue() brings result list in missorder

Bug#42495: updatexml: Assertion failed: xpath->context, file .\item_xmlfunc.cc, line 2507

Bug#38227: EXTRACTVALUE doesn't work with DTD declarations

Bug#43913: rpl_cross_version can't pass on conflicts complainig clash with --slave-load-tm

Bug#45511: rpl.rpl_binlog_corruption fails with warning messages in Valgrind

Bug#44091: libmysqld gets stuck waiting on mutex on initialization

Bug#43706: libmysqld segfaults when re-intialised

Bug#43733: Select on processlist let the embedded server crash (concurrent_innodb_safelog)

Bug#38293: Libmysqld crash in mysql_library_init if language file missing

Bug#39289: libmysqld.a calls exit() upon error

Bug#37995: Error message truncation in test "innodb" in embedded mode

Bug#34517: SHOW GLOBAL STATUS does not work properly in embedded server.

Bug#38522: 5 seconds delay when closing application using embedded server

MySQL Cluster fails to recover from an out-of-disk failure when using disk data. (Bug#17614)

Subquery optimization for IN is not as effective as for =.

Even if you use lower_case_table_names=2 (which enables MySQL to remember the case used for databases and table names), MySQL does not remember the case used for database names for the function DATABASE() or within the 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 command wait until the table is not being used in any transaction.

When inserting a big integer value (between 2⁶³ and 2⁶⁴–1) into a decimal or 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, OPTIMIZE TABLE, and REPAIR TABLE may cause problems on tables for which you are using INSERT DELAYED.

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

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.

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 nondeterministic (generally not a recommended practice, even outside of replication).

For example:

If and only if the preceding 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 is to add an ORDER BY clause to the aforementioned nondeterministic 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 file names are based on the server host name (if you don't specify a file name with the startup option). You have to use options such as --log-bin=old_host_name-bin if you change your host name to something else. Another option is to rename the old files to reflect your host name change (if these are binary logs, you need to edit the binary log index file and fix the binlog names there as well). See Section 5.1.2, “Server Command Options”.

mysqlbinlog does not delete temporary files left after a LOAD DATA INFILE command. See Section 4.6.7, “mysqlbinlog — Utility for Processing Binary Log Files”.

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

Due to the way table format (.frm) 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 implement 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.

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 2.10.5, “MIT-pthreads Notes”.

BLOB and TEXT values can't reliably be used in GROUP BY, 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 is 1024 and can be changed at server startup time or at runtime.

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 performed 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 larger than 63 bits (9223372036854775807) for anything other than bit fields.

You can have 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 the general query 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 it and executing mysqladmin refresh.

In an 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, using MySQL Server 3.23.x, you may 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 that do not have the ORDER BY columns in the result.

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 compatible types.

If you use ALTER TABLE to add a UNIQUE index to a table used in a MERGE table and then add a normal index on the MERGE table, the key order is different for the tables if there was an old, non-UNIQUE key 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.