"canceling statement due to statement timeout" for board lists issues query.

After turning on :graphql_board_lists for all of gitlab.com on June 1st, a few customers have reported seeing the following error:

An error occurred while fetching the board issues. Please reload the page.

As reported in Slack by @rkelly:

Hey team, it looks like we recently enabled a graphql_board_lists FF and have since had a few customer reports of the following error when viewing Issue Boards

An error occurred while fetching the board issues. Please reload the page.

I was able to correlate this to some kibana logs and a Sentry Issue.

Would somebody be able to confirm if the FF is the cause of these errors? Tickets listed in the

Kibana Log: https://log.gprd.gitlab.net/goto/e91300fca655afda6de8b79bfd403c84

Sentry Issue: https://sentry.gitlab.net/gitlab/gitlabcom/issues/2660698/?query=is%3Aunresolved%20correlation_id%3A01F79928SZE0J62FP27J9ZSWB1

---

An error occurred while fetching the board issues. Please reload the page. is shown when this graphql fails: lists_issues.query.graphql

The kibana log records the db query timing out PG::QueryCanceled: ERROR: canceling statement due to statement timeout for the graphql query.