MySQL

MySQL, the industry-leading open-source SQL database, is an accessible, easy-to-use relational database management system (RDBMS). As an alternative to Oracle and SQL server, MySQL offers features and capabilities that were once only available to users of expensive proprietary systems.

Notes: For a full list of changes go here. Upgrade from MySQL 5.7 to MySQL 8.0 is only supported using the in-place upgrade method. Downgrade from MySQL 8.0 to MySQL 5.7 (or from a MySQL 8.0 release to a previous MySQL 8.0 release) is not supported. The only supported alternative is to restore a backup taken before upgrading.

Bugs Fixed:

• NDB Cluster: EXPLAIN of a query executed with table access type eq_ref could also show a condition being pushed down, even when condition pushdown was not supported for the query. Now the access type is checked before NDB checks the condition for a possible pushdown optimization.
• This fix does not affect handling of tables which are part of a pushed join, for which NDB continues to support pushed conditions as before.
• InnoDB: Undo tablespaces remained unencrypted after enabling undo tablespace encryption at startup.
• InnoDB: Problematic macros introduced with undo tablespace DDL support in MySQL 8.0.14 were revised.
• InnoDB: Static thread local variables defined at the wrong scope were not released at thread exit.
• InnoDB: The performance_schema.data_locks LOCK_DATA column only showed the secondary index values of the locked record for a lock placed on a unique secondary index, which was not sufficient to ensure the uniqueness of identified records. The clustered index column values of the locked record are now appended.
• InnoDB: An incorrect count of transactions using a rollback segment for recovery of an XA transaction prevented an undo tablespace truncation operation from proceeding and left the purge thread busy checking for the undo tablespace to become empty.
• InnoDB: Invalid assertions were raised at startup after a failure to retrieve the space ID of a compressed file-per-table tablespace. The invalid assertion code was removed.
• InnoDB: Optimized InnoDB internal temporary tables did not support in-place UPDATE operations, which caused the number of delete-marked records to increase continuously. The large number of delete-marked records could cause longer than expected query execution times.
• InnoDB: The std::sort function in the Variance-Aware Transaction Scheduling (VATS) algorithm was replaced by the std::stable_sort function to preserve the original FIFO order for transactions of equal weight.
• InnoDB: Write-ahead did not work as expected due to an incorrectly initialized variable.