<!--IssueSummary start--> <details> <summary> Everyone can contribute. [Help move this issue forward](https://handbook.gitlab.com/handbook/marketing/developer-relations/contributor-success/community-contributors-workflows/#contributor-links) while earning points, leveling up and collecting rewards. </summary> - [Work on this issue](https://contributors.gitlab.com/manage-issue?action=work&projectId=278964&issueIid=30887) - [Close this issue](https://contributors.gitlab.com/manage-issue?action=close&projectId=278964&issueIid=30887) </details> <!--IssueSummary end--> Currently we're using this query to mark all these mirrors as failed. The query is always scoped to a project, so they're never more than a handful of rows to update. But Ideally we'd have an index for `project_id, last_update_started_at, last_update_at` after https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/31247 gets merged.