Remove experimental label of innodb_locking_fake_changes

[Stewart Smith]

Introduced in 5.5.28-29.2, this option to fake changes makes the fake transactions take no locks.

   When this variable is set to ``FALSE``, it makes fake transactions not to take any row locks. This feature was implemented because, although fake change transactions downgrade the requested exclusive (X) row locks to shared (S) locks, these S locks prevent X locks from being taken and block the real changes. However, this option is not safe to set to FALSE by default, because the fake changes implementation is not ready for lock-less operation for all workloads. Namely, if a real transaction will remove a row that a fake transaction is doing a secondary index maintenance for, the latter will fail. This option is considered experimental and might be removed in the future if lockless operation mode fixes are implemented.

This bug is to track removing the experimental label, calling the feature fully baked, or to remove the feature.

[Laurynas Biveinis (laurynas-biveinis)]

I think we should keep the experimental label. Fake changes should work with the least required locking automatically, and once this is implemented we should remove the option, which is a band-aid until then.

[Stewart Smith (stewart)]

Laurynas Biveinis <email address hidden> writes:
> I think we should keep the experimental label. Fake changes should work
> with the least required locking automatically, and once this is
> implemented we should remove the option, which is a band-aid until
> then.

I agree that for the time being we should keep it. Let's keep this bug
open to track it though.

--
Stewart Smith

[Shahriyar Rzayev (rzayev-sehriyar)]

Percona now uses JIRA for bug reports so this bug report is migrated to: https://jira.percona.com/browse/PS-2910