Add a foreign key to `merge_requests.head_pipeline_id`
What does this MR do?
This MR adds a foreign key to merge_requests.head_pipeline_id
.
Are there points in the code the reviewer needs to double check?
We already have an index on that field, so it should be easier to add a foreign key. However adding this foreign key will introduce locking on ci_pipelines
table, which is heavily used, and this might cause problems in case of running this migration when Sidekiq nodes are running.
What are the relevant issue numbers?
Closes gitlab-org/gitlab-ce#34065
Edited by Grzegorz Bizon