Re: Queries sometimes take 1000 times the normal time - Mailing list pgsql-performance

From Tom Lane
Subject Re: Queries sometimes take 1000 times the normal time
Date
Msg-id 28672.1062027548@sss.pgh.pa.us
Whole thread Raw
In response to Queries sometimes take 1000 times the normal time  ("Anders K. Pedersen" <akp@cohaesio.com>)
List pgsql-performance
"Anders K. Pedersen" <akp@cohaesio.com> writes:
> Currently there's only a few users in the database for testing purposes,
> and most of the time the user lookup's take 2-3 ms (I have syslog'ing of
> queries and duration turned on), but several times per hour the duration
> for one of the queries is 2-3 seconds (1000 times larger), while the
> surrounding lookups take the usual 2-3 ms.

One thing that comes to mind is that the slow query could be occurring
at the same time as a checkpoint, or some other cycle-chewing background
operation.  It's not clear why a checkpoint would slow things down that
much, though.  Anyway I'd suggest looking for such activities; once we
know if that's the issue or not, we can make some progress.

            regards, tom lane

pgsql-performance by date:

Previous
From: Neil Conway
Date:
Subject: Re: Simple queries take forever to run
Next
From: Jeff
Date:
Subject: Re: Sun vs a P2. Interesting results.