Re: max_standby_delay considered harmful

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Simon Riggs <simon(at)2ndquadrant(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: max_standby_delay considered harmful
Date: 2010-05-06 15:38:18
Message-ID: AANLkTiljAwtVO2Q0WBWyyWORq3Y0GJedKYUb3LmjXMuk@mail.gmail.com
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On Mon, May 3, 2010 at 11:37 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> I'm inclined to think that we should throw away all this logic and just
> have the slave cancel competing queries if the replay process waits
> more than max_standby_delay seconds to acquire a lock.  This is simple,
> understandable, and behaves the same whether we're reading live data or
> not.

Now that I've realized what the real problem is with max_standby_delay
(namely, that inactivity on the master can use up the delay), I think
we should do what Tom originally suggested here. It's not as good as
a really working max_standby_delay, but we're not going to have that
for 9.0, and it's clearly better than a boolean.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise Postgres Company

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