MySQL Community Edition is a freely downloadable version of the world's most popular open source database that is supported by an active community of open source developers and enthusiasts.
MySQL delivers enterprise features, including:
- Partitioning to improve performance and management of very large database environments
- Row-based/Hybrid Replication for improved replication security
- Event Scheduler to create and schedule jobs that perform various database tasks
- XPath Support
- Dynamic General/Slow Query Log
- Performance/Load Testing Utility (mysqlslap)
- Improved! Full Text Search (faster, new dev templates)
- Improved! Archive engine (better compression, more features)
- Improved! User session and problem SQL identification
- Improved! MySQL embedded library (libmysqld)
- Additional INFORMATION_SCHEMA objects
- Faster data import operations (parallel file load)
- ACID Transactions to build reliable and secure business critical applications
- Stored Procedures to improve developer productivity
- Triggers to enforce complex business rules at the database level
- Views to ensure sensitive information is not compromised
- Information Schema to provide easy access to metadata
- Pluggable Storage Engine Architecture for maximum flexibility
- Archive Storage Engine for historical and audit data
# Functionality Added or Changed
* yaSSL was upgraded from version 1.7.2 to 2.2.0.
# Bugs Fixed
* Security Fix: Bug #13510739 and Bug #63775 were fixed.
* Incompatible Change: An earlier change (in MySQL 5.1.59 and 5.5.16) was found to modify date-handling behavior in General Availability-status series (MySQL 5.1 and 5.5). This change has been reverted. The change was that several functions became more strict when passed a DATE() function value as their argument, thus they rejected incomplete dates with a day part of zero. These functions were affected: CONVERT_TZ(), DATE_ADD(), DATE_SUB(), DAYOFYEAR(), LAST_DAY(), TIMESTAMPDIFF(), TO_DAYS(), TO_SECONDS(), WEEK(), WEEKDAY(), WEEKOFYEAR(), YEARWEEK(). The previous behavior has been restored.
* Important Change: InnoDB Storage Engine: When a row grew in size due to an UPDATE operation, other (non-updated) columns could be moved to off-page storage so that information about the row still fit within the constraints of the InnoDB page size. The pointer to the new allocated off-page data was not set up until the pages were allocated and written, potentially leading to lost data if the system crashed while the column was being moved out of the page. The problem was more common with tables using ROW_FORMAT=DYNAMIC or ROW_FORMAT=COMPRESSED along with the Barracuda file format, particularly with the innodb_file_per_table setting enabled, because page allocation operations are more common as the .ibd tablespace files are extended. Still, the problem could occur with any combination of InnoDB version, file format, and row format. A related issue was that during such an UPDATE operation, or an INSERT operation that reused a delete-marked record, other transactions could see invalid data for the affected column, regardless of isolation level. The fix corrects the order of operations for moving the column data off the original page and replacing it with a pointer. Now if a crash occurs at the precise moment when the column data is being transferred, the transfer will not be re-run during crash recovery. In MySQL 5.1, this fix applies to the InnoDB Plugin, but not the built-in InnoDB storage engine.
* InnoDB Storage Engine: An erroneous assertion could occur, in debug builds only, when creating an index on a column containing zero-length values (that is, ''). (Bug #13654923)
* InnoDB Storage Engine: A DDL operation such as ALTER TABLE ... ADD COLUMN could stall, eventually timing out with an Error 1005: Can't create table message referring to fil_rename_tablespace.
* InnoDB Storage Engine: References to C preprocessor symbols and macros HAVE_purify, UNIV_INIT_MEM_TO_ZERO, and UNIV_SET_MEM_TO_ZERO were removed from the InnoDB source code. They were only used in debug builds instrumented for Valgrind. They are replaced by calls to the UNIV_MEM_INVALID() macro.
* InnoDB Storage Engine: A DDL operation for an InnoDB table could cause a busy MySQL server to halt with an assertion error: InnoDB: Failing assertion: trx->error_state == DB_SUCCESS The error occurred if the DDL operation was run while all 1023 undo slots were in use by concurrent transactions. This error was less likely to occur in MySQL 5.5 and 5.6, because raising the number of InnoDB undo slots increased the number of simultaneous transactions (corresponding to the number of undo slots) from 1K to 128K.
* InnoDB Storage Engine: With 1024 concurrent InnoDB transactions running concurrently and the innodb_file_per_table setting enabled, a CREATE TABLE operation for an InnoDB table could fail. The .ibd file from the failed CREATE TABLE was left behind, preventing the table from being created later, after the load had dropped. The fix adds error handling to delete the erroneous .ibd file. This error was less likely to occur in MySQL 5.5 and 5.6, because raising the number of InnoDB undo slots increased the number of simultaneous transactions needed to trigger the bug, from 1K to 128K.
* InnoDB Storage Engine: When copying a partitioned InnoDB table from a Linux system to a Windows system, you could encounter this error: 101115 14:19:53 [ERROR] Table .\test\d has no primary key in InnoDB data dictionary, but has one in MySQL! Normally, the solution to copy InnoDB tables from Linux to Windows is to create the tables on Linux with the lower_case_table_names option enabled. Partitioned tables, with #P# appended to the filename, were not covered by that solution.
* InnoDB Storage Engine: Server startup could produce an error for temporary tables using the InnoDB storage engine, if the path in the $TMPDIR variable ended with a / character. The error log would look like:
120202 19:21:26 InnoDB: Operating system error number 2 in a file operation.
InnoDB: The error means the system cannot find the path specified.
InnoDB: If you are installing InnoDB, remember that you must create
InnoDB: directories yourself, InnoDB does not create them.
120202 19:21:26 InnoDB: Error: trying to open a table, but could not
InnoDB: open the tablespace file './t/#sql7750_1_0.ibd'!
InnoDB: Have you moved InnoDB .ibd files around without using the
InnoDB: commands DISCARD TABLESPACE and IMPORT TABLESPACE?
InnoDB: It is also possible that this is a temporary table #sql...,
InnoDB: and MySQL removed the .ibd file for this.
The workaround for the problem was to create a similar temporary table again, copy its .frm file to tmpdir under the name mentioned in the error message (for example, #sql123.frm) and restart mysqld with tmpdir set to its normal value without a trailing slash, for example /var/tmp. On startup, MySQL would see the .frm file and issue DROP TABLE for the orphaned temporary table.
* A query that used an index on a CHAR column referenced in a BETWEEN clause could return invalid results.
* When the optimizer performed conversion of DECIMAL values while evaluating range conditions, it could produce incorrect results.
* When used with the --xml option, mysqldump --routines failed to dump any stored routines, triggers, or events.
* It was possible on replication slaves where FEDERATED tables were in use to get timeouts on long-running operations, such as Error 1160 Got an error writing communication packets. The FEDERATED tables did not need to be replicated for the issue to occur.
* If an attempt to initiate a statement failed, the issue could not be reported to the client because it was not prepared to receive any error messages prior to the execution of any statement. Since the user could not execute any queries, they were simply disconnected without providing a clear error. After the fix for this issue, the client is prepared for an error as soon as it attempts to initiate a statement, so that the error can be reported prior to disconnecting the user.
* Using myisamchk with the sort recover method to repair a table having fixed-width row format could cause the row pointer size to be reduced, effectively resulting in a smaller maximum data file size.
* Due to improper locking, concurrent inserts into an ARCHIVE table at the same time as repair and check operations on the table resulted in table corruption.