On Thu, Apr 16, 2020 at 4:43 AM Hamid Akhtar <hamid.akhtar@gmail.com> wrote: > My real question is whether vacuum should be preemptively complaining about prepared transactions or stale replication slots rather than waiting for transaction id to exceed the safe limit. I presume by the time safe limit is exceeded, vacuum's work would already have been significantly impacted.
Yeah, for my part, I agree that letting things go until the point where VACUUM starts to complain is usually bad. Generally, you want to know a lot sooner. That being said, I think the solution to that is to run a monitoring tool, not to overload the autovacuum worker with additional duties.
So is the concern performance overhead rather than the need for such a feature?
Any server running with prepared transactions enabled, more likely than not, requires a monitoring tool for tracking orphaned prepared transactions. For such environments, surely the overhead created by such a feature implemented in the server will create a lower overhead than their monitoring tool.
