ActiveRecord::StatementInvalid: PG::QueryCanceled: ERROR: canceling statement due to statement timeout

• https://sentry.gitlap.com/gitlab/gitlabcom/issues/46532/
• https://sentry.gitlap.com/gitlab/gitlabcom/issues/48281/
• https://sentry.gitlap.com/gitlab/gitlabcom/issues/72343/

PG::QueryCanceled: ERROR:  canceling statement due to statement timeout

  lib/gitlab/database/load_balancing/connection_proxy.rb:61:in `block in read_using_load_balancer'
    connection.send(name, *args, &block)
  lib/gitlab/database/load_balancing/load_balancer.rb:30:in `read'
    return yield host.connection
  lib/gitlab/database/load_balancing/connection_proxy.rb:60:in `read_using_load_balancer'
    @load_balancer.send(method) do |connection|
  lib/gitlab/database/load_balancing/connection_proxy.rb:39:in `select_all'
    read_using_load_balancer(:select_all, [arel, name, binds])
  app/models/merge_request.rb:897:in `all_commit_shas'
    column_shas = MergeRequestDiffCommit.where(merge_request_diff: merge_request_diffs).pluck('DISTINCT(sha)')
...
(143 additional frame(s) were not displayed)

ActiveRecord::StatementInvalid: PG::QueryCanceled: ERROR:  canceling statement due to statement timeout
: SELECT DISTINCT(sha) FROM "merge_request_diff_commits" WHERE "merge_request_diff_commits"."merge_request_diff_id" IN (SELECT "merge_request_diffs"."id" FROM "merge_request_diffs" WHERE "merge_request_diffs"."merge_request_id" = mr_id)

ActiveRecord::StatementInvalid: PG::QueryCanceled: ERROR:  canceling statement due to statement timeout
: SELECT DISTINCT(sha) FROM "merge_request_diff_commits" WHERE "merge_request_diff_commits"."merge_request_diff_id" IN (SELECT "merge_request_diffs"."id" FROM "merge_request_diffs" WHERE "merge_request_diffs"."merge_request_id" = mr_id)

/cc @markglenfletcher