Documentation Home
MySQL 5.5 Release Notes
Related Documentation Download these Release Notes
PDF (US Ltr) - 1.7Mb
PDF (A4) - 1.7Mb

MySQL 5.5 Release Notes  /  Changes in MySQL 5.5.9 (2011-02-07, General Availability)

Changes in MySQL 5.5.9 (2011-02-07, General Availability)

Functionality Added or Changed

  • The mysqladmin and mysqldump clients now have --default-auth and --plugin-dir options for specifying which authentication plugin and plugin directory to use. (Bug #58139, Bug #11765201)

  • sql_priv.h now includes an OPTION_ALLOW_BATCH flag for the transaction_allow_batching feature of MySQL NDB Cluster. (Bug #57604)

  • Boolean system variables can be enabled at run time by setting them to the value ON or OFF, but previously this did not work at server startup. Now at startup such variables can be enabled by setting them to ON or TRUE. Any other nonnumeric value is interpreted as OFF. (Bug #46393 improves on this such that ON, TRUE, OFF, and FALSE are recognized, and other values are invalid.) (Bug #51631, Bug #11759326)

    References: See also: Bug #46393, Bug #11754743.

  • In the audit plugin interface, the MYSQL_AUDIT_CONNECTION_CLASS event class was added, and the MYSQL_AUDIT_GENERAL_STATUS subclass was added to the MYSQL_AUDIT_GENERAL_CLASS event class. The new symbol definitions can be found in the plugin_audit.h header file.

Bugs Fixed

  • Security Fix: A security bug was fixed. (Bug #57952)

  • Incompatible Change: When auto_increment_increment is greater than one, values generated by a bulk insert that reaches the maximum column value could wrap around rather producing an overflow error.

    As a consequence of the fix, it is no longer possible for an auto-generated value to be equal to the maximum BIGINT UNSIGNED value. It is still possible to store that value manually, if the column can accept it. (Bug #39828, Bug #11749800)

  • Important Change; Partitioning: Date and time functions used as partitioning functions now have the types of their operands checked; use of a value of the wrong type is now disallowed in such cases. In addition, EXTRACT(WEEK FROM col_name), where col_name is a DATE or DATETIME column, is now disallowed altogether because its return value depends on the value of the default_week_format system variable. (Bug #54483, Bug #11761948)

    References: See also: Bug #57071, Bug #11764255.

  • Performance; InnoDB: An UPDATE statement for an InnoDB table could be slower than necessary if it changed a column covered by a prefix index, but did not change the prefix portion of the value. The fix improves performance for InnoDB 1.1 in MySQL 5.5 and higher, and the InnoDB Plugin for MySQL 5.1. (Bug #58912, Bug #11765900)

  • Performance; InnoDB: Synchronization inside InnoDB frequently involves the use of spin loops: while waiting, InnoDB executes a tight loop of instructions repeatedly to avoid having the InnoDB process and threads be rescheduled by the operating system. If the spin loops are executed too quickly, system resources are wasted, imposing a performance penalty on transaction throughput. Most modern processors implement the PAUSE instruction for use in spin loops, so the processor can be more efficient.

    InnoDB now uses the PAUSE instruction in its spin loops on all platforms where such an instruction is available. Previously, InnoDB used the PAUSE instruction only on Windows systems. Use of the PAUSE instruction increases overall performance with CPU-bound workloads, and provides the added benefit of minimizing power consumption during the execution of the spin loops. (Bug #58666)

  • Performance: Queries involving InnoDB tables in the INFORMATION_SCHEMA tables TABLE_CONSTRAINTS, KEY_COLUMN_USAGE, or REFERENTIAL_CONSTRAINTS were slower than necessary because statistics were rechecked more often than required, even more so when many foreign keys were present. The improvement to this may be of particular benefit to users of MySQL Enterprise Monitor with many monitored servers or tens of thousands of tables. (Bug #43818, Bug #11752585)

  • InnoDB; Partitioning: The partitioning handler did not pass locking information to a table's storage engine handler. This caused high contention and thus slower performance when working with partitioned InnoDB tables. (Bug #59013)

  • InnoDB: The presence of a double quotation mark inside the COMMENT field for a column could prevent a foreign key constraint from being created properly. (Bug #59197, Bug #11766154)

  • InnoDB: When multiple InnoDB buffer pools were enabled, SHOW ENGINE INNODB statements displayed information about each one, but not summary information combining statistics for the entire buffer pool subsystem. Now, the aggregated information is displayed in the BUFFER POOL AND MEMORY section, and information about individual buffer pool instances is displayed in a new INDIVIDUAL BUFFER POOL INFO section. (Bug #58461)

  • InnoDB: The command to create a debug build (cmake -DWITH_DEBUG ...) now automatically sets the InnoDB debugging flag UNIV_DEBUG on all platforms. Formerly, the UNIV_DEBUG flag might not be set for Windows platforms with Visual Studio and not on OS X with Xcode. (Bug #58279)

  • InnoDB: In InnoDB status output, the value for I/O sum[] could be incorrect, displayed as a very large number. (Bug #57600)

  • InnoDB: The server could crash with an assertion error, if a stored procedure, stored function, or trigger modified one InnoDB table containing an auto-increment column, and dropped another InnoDB table containing an auto-increment column. (Bug #56228)

  • InnoDB: It was not possible to query the information_schema.INNODB_TRX table while other connections were running queries involving BLOB types. (Bug #55397, Bug #11762763)

  • InnoDB: When the lower_case_table_names variable was set to 2, InnoDB could fail to restore a mysqldump dump of a table with foreign key constraints involving case-sensitive names. (Bug #55222)

  • InnoDB: The OPTIMIZE TABLE statement reset the auto-increment counter for an InnoDB table. Now the auto-increment value is preserved across this operation. (Bug #18274)

  • Partitioning: Failed ALTER TABLE ... TRUNCATE PARTITION statements were written to the binary log. (Bug #58147)

  • Partitioning: Failed ALTER TABLE ... PARTITION statements could cause memory leaks. (Bug #56380, Bug #11763641)

    References: See also: Bug #46949, Bug #11755209, Bug #56996, Bug #11764187.

  • Replication: While an INSERT DELAYED statement with a single inserted value does not return any visible warnings, such a warning could be still written into the error log. (Bug #57666, Bug #11764793)

    References: See also: Bug #49567.

  • Replication: When closing a session that used temporary tables, binary logging could sometimes fail with a spurious Failed to write the DROP statement for temporary tables to binary log. (Bug #57288)

  • Replication: Due to changes made in MySQL 5.5.3, settings made in the binlog_cache_size and max_binlog_cache_size server system variables affected both the binary log statement cache (also introduced in that version) and the binary log transactional cache (formerly known simply as the binary log cache). This meant that the resources used as a result of setting either or both of these variables were double the amount expected. To rectify this problem, these variables now affect only the transactional cache. The fix for this issue also introduces two new system variables binlog_stmt_cache_size and max_binlog_stmt_cache_size, which affect only the binary log statement cache.

    In addition, the Binlog_cache_use status variable was incremented whenever either cache was used, and Binlog_cache_disk_use was incremented whenever the disk space from either cache was used, which caused problems with performance tuning of the statement and transactional caches, because it was not possible to determine which of these was being exceeded when attempting to troubleshoot excessive disk seeks and related problems. This issue is solved by changing the behavior of these two status variables such that they are incremented only in response to usage of the binary log transactional cache, as well as by introducing two new status variables Binlog_stmt_cache_use and Binlog_stmt_cache_disk_use, which are incremented only by usage of the binary log statement cache.

    The behavior of the max_binlog_cache_size system variable with regard to active sessions has also been changed to match that of the binlog_cache_size system variable: Previously, a change in max_binlog_cache_size took effect in existing sessions; now, as with a change in binlog_cache_size, a change in max_binlog_cache_size takes effect only in sessions begun after the value was changed.

    For more information, see System Variables Used with Binary Logging, and Server Status Variables. (Bug #57275, Bug #11764443)

  • Replication: By default, a value is generated for an AUTO_INCREMENT column by inserting either NULL or 0 into the column. Setting the NO_AUTO_VALUE_ON_ZERO server SQL mode suppresses this behavior for 0, so that it occurs only when NULL is inserted into the column.

    This behavior is also followed on a replication slave (by the slave SQL thread) when applying events that have been logged on the master using the statement-based format. However, when applying events that had been logged using the row-based format, NO_AUTO_VALUE_ON_ZERO was ignored, which could lead to an assertion.

    To fix this issue, the value of an AUTO_INCREMENT column is no longer generated when applying an event that was logged using the row-based row format, as this value is already contained in the changes applied on the slave. (Bug #56662)

  • Replication: The Binlog_cache_use and Binlog_cache_disk_use status variables were incremented twice by a change to a table using a transactional storage engine. (Bug #56343, Bug #11763611)

    References: This issue is a regression of: Bug #50038.

  • Replication: The BINLOG statement modified the values of session variables, which could lead to problems with operations such as point-in-time recovery. One such case occurred when replaying a row-based binary log which relied on setting foreign_key_checks = OFF at the session level to create and populate a set of InnoDB tables having foreign key constraints. (Bug #54903)

  • Replication: mysqlbinlog printed USE statements to its output only when the default database changed between events. To illustrate how this could cause problems, suppose that a user issued the following sequence of statements:

    USE mydb;
    CREATE TABLE mytable (column_definitions);
    USE mydb;
    CREATE TABLE mytable (column_definitions);

    When played back using mysqlbinlog, the second CREATE TABLE statement failed with Error: No Database Selected because the second USE statement was not played back, due to the fact that a database other than mydb was never selected.

    This fix ensures that mysqlbinlog outputs a USE statement whenever it reads one from the binary log. (Bug #50914, Bug #11758677)

  • Replication: Previously, when a statement failed with a different error on the slave than on the master, the slave SQL thread displayed a message containing:

    • The error message for the master error code

    • The master error code

    • The error message for the slaves error code

    • The slave error code

    However, the slave has no information with which to fill in any print format specifiers for the master message, so it actually displayed the message format string. To make it clearer that the slave is not displaying the actual message as it appears on the master, the slave now indicates that the master part of the output is the message format, not the actual message. For example, previously the slave displayed information like this:

    Error: "Query caused different errors on master and slave. Error
    on master: 'Duplicate entry '%-.192s' for key %d' (1062), Error on
    slave: 'no error' (0). Default database: 'test'. Query: 'insert
    into t1 values(1),(2)'" (expected different error codes on master
    and slave)

    Now the slave displays this:

    Error: "Query caused different errors on master and slave. Error
    on master: message format='Duplicate entry '%-.192s' for key %d'
    error code=1062 ; Error on slave: actual message='no error', error
    code=0. Default database: 'test'. Query: 'insert into t1 values(1),(2)'"
    (expected different error codes on master and slave)

    (Bug #46697)

  • Replication: When an error occurred in the generation of the name for a new binary log file, the error was logged but not shown to the user. (Bug #46166)

    References: See also: Bug #37148, Bug #11748696, Bug #40611, Bug #11750196, Bug #43929, Bug #51019.

  • OS X: On OS X, a configuration error caused the preference pane to fail. (Bug #51264)

  • Solaris: On Solaris, the MySQL build failed if it was configured with debugging enabled. (Bug #58699)

  • Solaris: On Solaris, time-related functions such as NOW() or SYSDATE() could return a constant value. (Bug #42054)

  • Comparisons of aggregate values with TIMESTAMP values were incorrect. (Bug #59330, Bug #11766259)

  • For DIV expressions, assignment of the result to multiple variables could cause a server crash. (Bug #59241, Bug #11766191)

    References: See also: Bug #8457.

  • MIN(year_col) could return an incorrect result in some cases. (Bug #59211, Bug #11766165)

  • mysqlslap failed to check for a NULL return from mysql_store_result() and crashed trying to process the result set. (Bug #59109, Bug #11766074)

  • In a subquery, a UNION with no referenced tables (or only a reference to the DUAL virtual table) did not permit an ORDER BY clause. (Bug #58970, Bug #11765950)

  • cmake -DBUILD_CONFIG=mysql_release on Linux previously required libaio to be linked in. Now it is possible to specify -DIGNORE_AIO_CHECK to build without libaio. (Bug #58955, Bug #11765940)

  • Configuring MySQL with -DWITHOUT_PERFSCHEMA_STORAGE_ENGINE=1 caused build failures. (Bug #58953)

  • Several Valgrind warnings were fixed. (Bug #58948, Bug #59021)

  • OPTIMIZE TABLE for an InnoDB table could raise an assertion if the operation failed because it had been killed. (Bug #58933, Bug #11765920)

  • If max_allowed_packet was set larger than 16MB, the server failed to reject too-large packets with Packet too large errors. (Bug #58887, Bug #11765878)

  • A NOT IN predicate with a subquery containing a HAVING clause could retrieve too many rows, when the subquery itself returned NULL. (Bug #58818, Bug #11765815)

  • Release builds on Linux now are compiled with WITH_FAST_MUTEXES enabled. (Bug #58766, Bug #11765769)

  • EXPLAIN could crash for queries that accessed two derived tables. (Bug #58730)

  • Issuing EXPLAIN EXTENDED for a query that would use condition pushdown could cause mysqld to crash. (Bug #58553, Bug #11765570)

  • An assertion could be raised for queries for which the optimizer could choose between Index Merge range access or const ref access methods. (Bug #58456)

  • If MySQL was built with Visual Studio Express, the project wixca was not built. (Bug #58411)

  • EXPLAIN could crash for queries that used GROUP_CONCAT(). (Bug #58396)

  • CMake polluted the source tree by writing installation-related temporary files there. (Bug #58372)

  • Security context references in were rewritten for improved DTrace compatibility. (Bug #58350)

  • The ucs2 character set does not support characters outside the Basic Multilingual Plane (BMP), but converting to ucs2 a string containing such characters did not produce a conversion-failure warning. (Bug #58321)

  • A Valgrind failure occurred in fn_format when called from archive_discover. (Bug #58205, Bug #11765259)

  • CMake did not add LINK_LIBRARIES for MYSQL_ADD_PLUGIN for libmysqld. (Bug #58158)

  • An assertion could be raised if the server was closing a session at the same time the session was being killed by another thread. (Bug #58136)

  • Condition pushdown optimization could push down conditions with incorrect column references. (Bug #58134, Bug #11765196)

  • Configuration with maintainer mode enabled resulted in errors when compiling with icc. (Bug #57991, Bug #58871)

  • An ORDER BY clause was bound to the incorrect substatement when used in UNION context. (Bug #57986)

  • The BIT_AND() function could return incorrect results when a join returned no matching rows. (Bug #57954)

  • If the set of values aggregated with AVG(DISTINCT) contained a NULL value, the function result could be incorrect. (Bug #57932)

  • In rare cases, LIKE expressions failed for an indexed column that used a collation containing contractions. (Bug #57737)

  • Unnecessary subquery evaluation in contexts such as statement preparation or view creation could cause a server crash. (Bug #57703)

  • View creation could produce Valgrind warnings. (Bug #57352)

  • NULL geometry values could cause a crash in Item_func_spatial_collection::fix_length_and_dec. (Bug #57321)

  • It was possible to compile mysqld with Performance Schema support but with a dummy atomic-operations implementation, which caused a server crash. This problem does not affect binary distributions. It is helpful as a safety measure for users who build MySQL from source. (Bug #56769)

  • The cp1251 character set did not properly support the Euro sign (0x88). For example, converting a string containing this character to utf8 resulted in '?' rather than the utf8 Euro sign. (Bug #56639)

  • Some unsigned system variables could be displayed with negative values. (Bug #55794)

  • CREATE DATABASE and DROP DATABASE caused mysql --one-database to lose track of the statement-filtering context. (Bug #54899)

  • An assertion could be raised during concurrent execution of DROP DATABASE and REPAIR TABLE if the drop deleted a table's .TMD file at the same time the repair tried to read details from the old file that was just removed.

    A problem could also occur when DROP TABLE tried to remove all files belonging to a table at the same time REPAIR TABLE had just deleted the table's .TMD file. (Bug #54486)

  • After compilation from source, all header files were installed in the same directory, even those that should be installed into subdirectories of the installation include directory. (Bug #51925)

  • When mysqld printed crash dump information, it incorrectly indicated that some valid pointers were invalid. (Bug #51817)

  • On FreeBSD, if mysqld was killed with a SIGHUP signal, it could corrupt InnoDB .ibd files. (Bug #51023, Bug #11758773)

  • An assertion could be raised if −1 was inserted into an AUTO_INCREMENT column by a statement writing more than one row. (Bug #50619, Bug #11758417)

  • If a client supplied a user name longer than the maximum 16 characters permitted for names stored in the MySQL grant tables, all characters were being considered significant when checking for a match. Historically, only the first 16 characters were used for matching; this behavior was restored. (Bug #49752)

  • The my_seek() and my_tell() functions ignored the MY_WME flag when they returned an error, which could cause client programs to hang. (Bug #48451)

  • During assignment of values to system variables, legality checks on the value range occurred too late, preventing proper error checking. (Bug #43233)

  • If the remote server for a FEDERATED table could not be accessed, queries for the INFORMATION_SCHEMA.TABLES table failed. (Bug #35333)