Re: Will switchover still need a checkpoint in 9.1 SR Hot Standby

From: Simon Riggs <simon(at)2ndQuadrant(dot)com>
To: Hannu Krosing <hannu(at)2ndquadrant(dot)com>
Cc: PG Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Will switchover still need a checkpoint in 9.1 SR Hot Standby
Date: 2011-08-07 09:01:22
Message-ID: CA+U5nM+8sGAOrrTSfSYwSJn3jKVEkXNmSBkLALw22p2Vombhbg@mail.gmail.com
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On Sun, Aug 7, 2011 at 8:57 AM, Hannu Krosing <hannu(at)2ndquadrant(dot)com> wrote:
> In 9.0 (as in earlier versions) a former standby host has to do a full
> checkpoint before becoming available as an independent database instance
> in either switchover or failover scenarios.
>
> For most combinations of of bigger than minimal shared buffers and
> non-memory-speed disks this can take from several seconds to tens of
> minutes on busy systems.

For switchover, you issue a checkpoint first, to reduce this time as
much as possible.

> Is the pre-activation checkpoint still required in 9.1 ?

Yes, but I've found a way to remove them in 9.2 and will be patching that soon.

--
 Simon Riggs                   http://www.2ndQuadrant.com/
 PostgreSQL Development, 24x7 Support, Training & Services

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