Add NOT NULL constraint to merge_request_context_commits.merge_request_id
As part of &12795 we need to add sharding keys to all our tables. merge_request_context_commits
already has merge_request_id
from way-back, however sharding keys are required to be NOT NULL
so we will need to embark on the multi-release process of migrating that column, as outlined here: https://docs.gitlab.com/ee/development/database/not_null_constraints.html#add-a-not-null-constraint-to-an-existing-column
By not having this column as NOT NULL
we're unable to use desired_sharding_key
to automatically backfill this table.
This will delay completion of adding sharding keys to tables that want to backfill their own sharding keys from merge_request_context_commits
.
Similar to #444222
Edited by Kerri Miller