Thread

Re: can a blocked transaction affect the performance of one that is blocking it?

Nikolay Samokhvalov <nik@postgres.ai> — 2024-12-09T23:10:32Z

On Mon, Dec 9, 2024 at 13:16 Eric Schwarzenbach <subscriber@blackbrook.org>
wrote:

> Hi,
>
> Could one transaction (one that should be relatively simple and short)
> cause another complex, long running transaction (involving INSERTS, on a
> table the first transaction may be reading from) to take many orders of
> magnitude longer than it would normally? (short of competing for system
> resources, like CPU time etc, of course)
>
> I don't believe my scenario involved a deadlock but I expect my short
> transaction was probably blocked by my long one. Does it make any sense
> that this could very significantly affect the performance of the
> non-blocked transaction?
>
> Thanks,
>
> Eric


Have you tried wait event analysis (looking at wait_event_type, wait_event,
state, query samples from pg_stat_activity)?

>