Instrument sub-transactions created by ActiveRecord
What does this MR do?
We've experience performance degradations related to SubtransControlLocks
blocking CI/CD builds queuing queries. We want to understand where do the subtransactions come from. See gitlab-com/gl-infra/production#5152 (comment 629653355) for more details.
Conformity
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I have added information for database reviewers in the MR description. -
I have self-reviewed this MR per code review guidelines. -
This change is backwards compatible across updates.
Edited by Grzegorz Bizon