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Re: Hot Standby Lagging Behind

From: Prima Chairunnanda <prima(dot)ch(at)gmail(dot)com>
To: Lonni J Friedman <netllama(at)gmail(dot)com>
Cc: pgsql-novice(at)postgresql(dot)org
Subject: Re: Hot Standby Lagging Behind
Date: 2012-08-25 19:33:11
Message-ID: CAHfRcypmtzuyLt2wPUqQ09A2TQzPof=Ntse=uMWgh1oBoxgtaA@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-novice
Yes, they have exactly the same specification.

Prima

On Sat, Aug 25, 2012 at 2:33 PM, Lonni J Friedman <netllama(at)gmail(dot)com>wrote:

> Are both servers identical hardware?
>
> On Sat, Aug 25, 2012 at 12:37 AM, Prima Chairunnanda <prima(dot)ch(at)gmail(dot)com>
> wrote:
> > Hi Everyone,
> >
> > I have some questions about the PostgreSQL streaming replication
> feature. I
> > have been able to setup a hot-standby server, and I can see updates on
> the
> > master server being replayed on the standby server.
> >
> > However I notice that once I start making read-only queries, the standby
> > starts lagging behind the master server. After a while, the delay can
> reach
> > over 1 minute, even though I set the max_standby_streaming_delay
> parameter
> > to 15s. I am under the impression that once a WAL record is lagging 15s
> > behind, then it should trump any read-only queries in the system.
> >
> > Below are the values of pg_last_xlog_receive_location and
> > pg_last_xlog_replay_location at several time points
> >
> >  now 03:06:16
> >  pg_last_xlog_receive_location  0/59A31620
> >  pg_last_xlog_replay_location  0/599A6B90
> >
> >  now 03:07:18
> >  pg_last_xlog_receive_location 0/59A98460
> >  pg_last_xlog_replay_location 0/59A1BE58
> >
> >  now 03:07:31
> >  pg_last_xlog_receive_location 0/59AA8F48
> >  pg_last_xlog_replay_location 0/59A22288
> >
> > So as we can see the WAL record at 0/59A31620 was received at 03:06:16,
> but
> > more than a minute later at 03:07:31, it still hasn't been replayed.
> >
> > Am I configuring the wrong thing? Is there an option to increase the
> > priority of the WAL replay once it has been lagging for a certain amount
> of
> > WAL record?
> >
> > Thanks in advance for your help.
> >
> > Prima
>

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