gitlab-org--gitlab-foss/changelogs/unreleased/39054-activerecord-statementinvalid-pg-querycanceled-error-canceling-statement-due-to-statement-timeout.yml

---
title: Stop merge requests with thousands of commits from timing out
merge_request: 15063
author:
type: performance
Avoid hitting statement timeout finding MR pipelines For MRs with many thousands of commits, `SELECT DISTINCT(sha)` will be very slow. What we can't do to fix this: 1. Add an index. Postgres won't use it for DISTINCT without a lot of ceremony. 2. Do the `uniq` in Ruby. That can still be very slow with hundreds of thousands of commits. 3. Use a subquery. We haven't removed the `st_commits` column yet, but we will soon. Until 3 is available to us, we can just do 2, but also add a limit clause. There is no ordering, so this may return different results, but our goal with these MRs is just to get them to load, so it's not a huge deal. 2017-10-27 09:20:55 -04:00			`---`
			`title: Stop merge requests with thousands of commits from timing out`
			`merge_request: 15063`
			`author:`
			`type: performance`