Percona Server for MySQL 5.7.39-42 (2022-08-15)¶
Percona Server for MySQL is a free, fully compatible, enhanced, and open source drop-in replacement for any MySQL database. It provides superior performance, scalability, and instrumentation.
Percona Server for MySQL is trusted by thousands of enterprises to provide better performance and concurrency for their most demanding workloads. It delivers more value to MySQL server users with optimized performance, greater performance scalability and availability, enhanced backups, and increased visibility. Commercial support contracts are available.
Improvements and bug fixes provided by Oracle for MySQL 5.7.39 and included in Percona Server for MySQL are the following:
- To provide process information, the
SHOW PROCESSLISTstatement collects thread data from all active threads. Since the implementation iterates across active threads from within the thread manager while holding a global mutex, it has a negative impact on performance, particularly on busy systems.
Now, an alternative
SHOW PROCESSLIST implementation is available based on the new Performance Schema processlist table. This implementation queries active thread data from the Performance Schema rather than the thread manager and does not require a mutex:
To enable the alternative implementation, enable the
For new installations of MySQL 5.7.39, or higher, the processlist table is automatically created in the Performance Schema. It is not created automatically by an upgrade. If you are upgrading from an earlier version of MySQL 5.7, and want to use the Performance Schema implementation of processlist, create the table manually.
Find more information in the Creating the processlist table.
The alternative implementation of
SHOW PROCESSLISTalso applies to the mysqladmin processlist command.
The alternative implementation does not apply to the
INFORMATION_SCHEMA PROCESSLISTtable or the
COM_PROCESS_INFOcommand of the MySQL client/server protocol.
To ensure that the default and alternative implementations give the same information, check the configuration requirements in The processlist Table.
MySQL removes a 4GB tablespace file size limit on Windows 32-bit systems. The limit was set because of an incorrect calculation performed while extending the tablespace.
When, during a session, an incorrect value for the
binlog_checksumsystem variable is set, a
COM_BINLOG_DUMPcommand ran in the same session to request a binary log stream from a source fails. Now, the server validates the specified checksum value before starting the checksum algorithm setup process.
Find the full list of bug fixes and changes in the MySQL 5.7.39 Release Notes.
Deprecation and removal¶
myisam_repair_threadssystem variable has been removed.
--parallel-recoveroption has been removed.
SHOW PROCESSLIST statement now displays an extra field
TIME_MS field provides the information about the time in milliseconds that the thread has been in its current state.
DICT_TF2_FLAG_SETwas used instead of
PS-8174: MySQL crashed at shutdown with
buf0flu.cc:3567:UT_LIST_GET_LEN(buf_pool->flush_list) == 0assertion.
To contribute to the documentation, review the Documentation Contribution Guide