Release of Vitess v12.0.4

Major Changes

Cluster management

A race condition #9819 that happens when running PlannedReparentShard was fixed through #9859.

Query Serving

Two major bugs on UNION are fixed via this release. The first one, #10257, solves an issue around the UNION executor, where the execution context was not handled properly in a concurrent environment. The second one, #9945, was detected by one of our UNION tests becoming flaky in the CI, it got solved by #9979, which focuses on improving the concurrency of UNION executions.

A panic when ordering results in descending order on a hash vindex is also fixed. The original issue can be found here #10019.

Changelog

Bug fixes

Cluster management

• Fix the race between PromoteReplica and replication manager tick #9859

Query Serving

• Route explain table plan to the proper Keyspace #10028
• Multiple fixes to UNION planning and execution #10344

The release includes 5 commits (excluding merges)

Thanks to all our contributors: @GuptaManan100, @frouioui, @systay