Got it — you’re looking to clean/trim the

event_resources

data. In Prefect 3.x this is generally handled by pruning old events; the associated

event_resources

rows are removed with them via foreign keys. Here are docs and a safe approach. Useful docs - Database maintenance (retention, pruning, and Postgres tips): Database maintenance - Events concepts (what gets stored and why): Events concepts - Event persister API (batch deletion helper used by the server): Event persister API - Settings reference (events retention setting): Settings reference Options to clean up 1) Configure automatic retention (recommended) - Set an environment variable on your Prefect Server to control how long events are kept: -

PREFECT_SERVER_EVENTS_RETENTION_PERIOD

(default is 7 days) - After you set this and restart the server, old events (and their related

event_resources

) will be pruned over time. 2) One-time manual cleanup in Postgres - Preview what will be deleted:

SELECT e.id, e.occurred
FROM events e
WHERE e.occurred < now() - interval '30 days'
ORDER BY e.id
LIMIT 1000;

- Delete in batches to avoid long locks (this will also delete from

event_resources

if there’s ON DELETE CASCADE from

events

):

DELETE FROM events
WHERE id IN (
  SELECT id FROM events
  WHERE occurred < now() - interval '30 days'
  ORDER BY id
  LIMIT 10000
);

- If your schema does not have ON DELETE CASCADE, delete from

event_resources

first:

DELETE FROM event_resources er
WHERE er.event_id IN (
  SELECT id FROM events
  WHERE occurred < now() - interval '30 days'
  ORDER BY id
  LIMIT 10000
);

- Run the batch DELETE repeatedly until it affects 0 rows. - After large deletions, use Postgres maintenance to reclaim space (e.g.,

pg_repack

is generally preferred over

VACUUM FULL

for minimal locking). Questions to tailor guidance - Are you running Prefect Cloud or self-hosted Prefect Server? - What database/version are you using (Postgres assumed)? - How much history do you want to keep (e.g., 7, 30, 90 days)? - Do you know if your

events → event_resources

foreign key has ON DELETE CASCADE? If you share those details, I can suggest exact SQL and steps for your environment.