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Re: Hot Standby and handling max_standby_delay

From: Dimitri Fontaine <dfontaine(at)hi-media(dot)com>
To: Simon Riggs <simon(at)2ndQuadrant(dot)com>
Cc: Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Hot Standby and handling max_standby_delay
Date: 2010-01-16 13:08:21
Message-ID: m2zl4enqnu.fsf@hi-media.com (view raw or flat)
Thread:
Lists: pgsql-hackers
Simon Riggs <simon(at)2ndQuadrant(dot)com> writes:
> On Fri, 2010-01-15 at 20:50 +0200, Heikki Linnakangas wrote:
> Yes, it does. And I know you're thinking along those lines because we
> are concurrently discussing how to handle re-connection after updates.

With my State Machine proposal, we could only apply max_standby_delay if
in sync state, and cancel query unconditionally otherwise.

> The alternative is this: after being disconnected for 15 minutes we
> reconnect. For the next X minutes the standby will be almost unusable
> for queries while we catch up again.

That's it. And it could be the cause of another GUC, do we want to give
priority to catching-up to get back in sync, or to running queries. That
would affect to when we apply max_standby_delay, and when set to prefer
running queries it'd apply in any state as soon as we accept connections.

Regards,
-- 
dim

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Subject: Archive recovery crashes on win32 in HEAD - hot standby related?
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