Re: Hot standby, running xacts, subtransactions

From: Robert Treat <xzilla(at)users(dot)sourceforge(dot)net>
To: pgsql-hackers(at)postgresql(dot)org
Cc: Simon Riggs <simon(at)2ndquadrant(dot)com>, Josh Berkus <josh(at)agliodbs(dot)com>
Subject: Re: Hot standby, running xacts, subtransactions
Date: 2009-03-03 02:11:55
Message-ID: 200903022111.55567.xzilla@users.sourceforge.net
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On Wednesday 25 February 2009 16:43:54 Simon Riggs wrote:
> On Wed, 2009-02-25 at 13:33 -0800, Josh Berkus wrote:
> > > You raised that as an annoyance previously because it means that
> > > connection in hot standby mode may be delayed in cases of heavy,
> > > repeated use of significant numbers of subtransactions.
> >
> > While most users still don't use explicit subtransactions at all,
> > wouldn't this also affect users who use large numbers of stored
> > procedures?
>
> If they regularly use more than 64 levels of nested EXCEPTION clauses
> *and* they start their base backups during heavy usage of those stored
> procedures, then yes.
>

We have stored procedrues that loop over thousands of records, with
begin...exception blocks in that loop, so I think we do that. AFAICT there's
no way to tell if you have it wrong until you fire up the standby (ie. you
can't tell at the time you make your base backup), right ?

--
Robert Treat
Conjecture: http://www.xzilla.net
Consulting: http://www.omniti.com

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