# What this PR does
Adds an index on the `started_at` column in the `alerts_alertgroup`
table. For the alert groups query used by the
`check_escalation_finished_task`, this resulted in a huge performance
boost, taking the query time from 89mins to 4secs (on our largest
production dataset).
## Which issue(s) this PR fixes
closes#724
closes https://github.com/grafana/oncall-private/issues/1713
## Checklist
- [x] Unit, integration, and e2e (if applicable) tests updated
- [x] Documentation added (or `pr:no public docs` PR label added if not
required)
- [x] `CHANGELOG.md` updated (or `pr:no changelog` PR label added if not
required)
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