Re: Query performance inconsistant. - Mailing list pgsql-general

From Tom Lane
Subject Re: Query performance inconsistant.
Date
Msg-id 18989.1157731555@sss.pgh.pa.us
Whole thread Raw
In response to Re: Query performance inconsistant.  (Matthew Schumacher <matt.s@aptalaska.net>)
List pgsql-general
Matthew Schumacher <matt.s@aptalaska.net> writes:
> Here is the proc that has very inconsistent (anywhere from 25ms to
> 8000ms) performance:
> ...
> This setup, with concurrency, is returning very inconsistent query
> performance.  Sometimes its very fast, other times it's slow and waits.
>  This makes me think I have a table locking issue, but I'm not sure
> since pg_locks rarely reports more than this:

Yeah, I suspect a locking issue too, but you won't find out what it is
unless you can capture the content of pg_locks at a time when the proc
is being delayed.

You could try making the proc do
    LOCK TABLE ... IN ROW EXCLUSIVE MODE NOWAIT
inside an exception block, catching the error, and logging the contents
of pg_locks to someplace.

            regards, tom lane

pgsql-general by date:

Previous
From: Poul Jensen
Date:
Subject: ECPG - how to fetch then sort strings
Next
From: Martijn van Oosterhout
Date:
Subject: Re: ECPG - how to fetch then sort strings