Re: SSI patch version 14

From: Jeff Davis <pgsql(at)j-davis(dot)com>
To: Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov>
Cc: heikki(dot)linnakangas(at)enterprisedb(dot)com, simon(at)2ndQuadrant(dot)com, markus(at)bluegap(dot)ch, pgsql-hackers(at)postgresql(dot)org
Subject: Re: SSI patch version 14
Date: 2011-02-06 19:08:37
Message-ID: 1297019317.27157.157.camel@jdavis
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On Sat, 2011-02-05 at 14:43 -0600, Kevin Grittner wrote:
> "Kevin Grittner" wrote:
>
> > So now that I'm sure we actually do need code there, I'll add it.
>
> In working on this I noticed the apparent need to move two calls to
> PredicateLockTuple a little bit to keep them inside the buffer lock.
> Without at least a share lock on the buffer, it seems that here is a
> window where a read could miss the MVCC from a write and the write
> could fail to see the predicate lock. Please see whether this seems
> reasonable:
>
> http://git.postgresql.org/gitweb?p=users/kgrittn/postgres.git;a=commitdiff;h=7841a22648c3f4ae46f674d7cf4a7c2673cf9ed2

What does PredicateLockTuple do that needs a share lock? Does a pin
suffice?

Regards,
Jeff Davis

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