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Re: pgsql: Resolve timing issue with logging locks for Hot Standby.

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: Simon Riggs <simon(at)2ndquadrant(dot)com>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-committers(at)postgresql(dot)org
Subject: Re: pgsql: Resolve timing issue with logging locks for Hot Standby.
Date: 2012-01-30 14:12:17
Message-ID: (view raw or whole thread)
Lists: pgsql-committers
On Mon, Jan 30, 2012 at 4:13 AM, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
> On Mon, Jan 30, 2012 at 12:30 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> Simon Riggs <simon(at)2ndQuadrant(dot)com> writes:
>>> Resolve timing issue with logging locks for Hot Standby.
>>> We log AccessExclusiveLocks for replay onto standby nodes,
>>> but because of timing issues on ProcArray it is possible to
>>> log a lock that is still held by a just committed transaction
>>> that is very soon to be removed. To avoid any timing issue we
>>> avoid applying locks made by transactions with InvalidXid.
>>> Simon Riggs, bug report Tom Lane, diagnosis Pavan Deolasee
>> I see this was only applied to HEAD.  Wouldn't back-patching be in
>> order?  The problem is in 9.1 as well, no?
> Yes, it is. I prefer to give a little time before backpatching to
> avoid mistakes (of my own making), especially since we're busy enough
> not to want to divert energy to other releases right now. The patch
> will make it in before next minor release.

If it's going to go in before the next minor release, there's no real
value in holding off, is there?

Robert Haas
The Enterprise PostgreSQL Company

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