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
# Bugs Fixed
* InnoDB; Partitioning: When OPTIMIZE TABLE rebuilt a partitioned InnoDB table, it placed the resulting partition tablespace files (*.ibd files) in the default data directory instead of the directory specified using the DATA DIRECTORY option.
* InnoDB: Running REPLACE operations on multiple connections resulted in a hang.
* InnoDB: MySQL stalled when syncing the InnoDB full-text index cache.
* InnoDB: A CREATE TABLE ... DATA DIRECTORY operation failed to create a table while innodb_flush_method was set to O_DIRECT.
* InnoDB: The innodb_open_files setting could exceed the open files limit.
* Replication: Issuing STOP SLAVE caused a spurious Error reading packet from server: Lost connection to MySQL server during query message to be written to the error log. With this fix, when connection to the master is lost, the abort_slave flag is checked and the error message is printed only if the flag is not set.
* Replication: In Slave_worker::write_info(), DBUG_ENTER() had “Master_info::write_info” as its argument instead of “Slave_worker::write_info”. This fix corrects the argument. Thanks to Stewart Smith for the patch.
* Replication: When a multi-threaded slave stopped with an error, the same error message was printed three times. Now, the SQL thread's kill acceptance status is saved, and only printed once.
* Replication: mysqlbinlog --verbose displayed BINARY and VARBINARY data as ordinary strings, causing any single quote (“'”) or backslash (“\”) among the data to be printed as such, which was confusing to the users and, in the case of a backslash, caused the next character to be skipped. This fix makes mysqlbinlog print the characters' hexadecimal values (“\x27” for single quote and “\x5c” for backslash) instead.
* Replication: The test case main.merge failed when the variables binlog_format was set to “ROW,” as the server tried to get information for table creation for a child table before it was opened. With this fix, the server skips getting information for the table in the situation.
* Replication: If a query on a master generated an error and partial results were written to the binary log, for example due to a DROP TABLE IF EXISTS statement applying to multiple tables that would break foreign key constraints, when a slave configured with replication filters encountered the query it could be incorrectly binary logged. This caused errors such as:
* Last_SQL_Error: Query caused different errors on master and slave. Error on master: message (format)='Cannot delete or update a parent row: a foreign key constraint fails' error code=1217 ; Error on slave: actual message='no error', error code=0. Default database: 'db1'. Query: 'DROP TABLE IF EXISTS `table1` /* generated by server */'
* There were two fixes required for this bug.
- If a DROP TABLE statement used to drop a single table fails, to avoid partial results causing this bug the query is not written to the binary log. If a DROP TABLE statement used to drop a list of tables fails, any partial results it generates are written to the binary log with an error.
- When a query that generates an error as expected was received by a slave but it was skipped due to replication filters, the slave was incorrectly checking the error. The fix ensures that this comparison of the expected error from the master with the actual error from the slave does not happen.
* Integer overflow could occur during client handshake processing, leading to a server exit.
* The System-V initialization script for RHEL6 or older failed to enable the mysqld service by default.
* When ExtractValue() found no match for the supplied expression, it returned NULL instead of an empty string as expected.
* This issue affected MySQL 5.6.28 and 5.6.29 only.
* Improper host name checking in X509 certificates could permit man-in-the-middle attacks.
* A boolean mode full-text search caused a segmentation fault.
* Concurrent selecting and flushing of a FEDERATED table while killing connections accessing it could result in a server exit.
* Executing GRANT PROXY statements after altering the definition of the mysql.user system table could result in a server exit.
* Certain error messages included part of the SQL statement that produced them, possibly exposing data.
* The Performance Schema assumed that tables named using a #sql prefix were temporary and could be ignored. But it is possible to create nontemporary tables using that prefix. The Performance Schema now uses table attributes other than the name to identify temporary tables.
* Character set conversion operations on NULL parameters to prepared statements could cause a server exit.
* Loose Index Scan was not chosen for queries that had an equality condition.
* A MySQL 5.6 server exited during startup if used with a 5.7 data directory due to the change in 5.7 of the mysql.plugin table from MyISAM to InnoDB. A safe shutdown now occurs in this circumstance.
* For INSERT and UPDATE operations that caused FOREIGN KEY constraint violations, errors were reported rather than warnings when the IGNORE keyword was used.
* For some queries, an Index Merge access plan was chosen over a range scan when the cost for the range scan was the same or less.
* Certain queries could raise an assertion when a internal string operation produced a NULL pointer rather than an empty string.
* EXPLAIN for SELECT ... FOR UPDATE statements acquired locks.
* Processlist state information was not updated correctly for LOAD DATA INFILE and could show a state different from executing.