From: | Bruce Momjian <bruce(at)momjian(dot)us> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | Robert Haas <robertmhaas(at)gmail(dot)com>, Tomas Vondra <tv(at)fuzzy(dot)cz>, Thom Brown <thom(at)linux(dot)com>, pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: change in LOCK behavior |
Date: | 2012-10-11 01:11:18 |
Message-ID: | 20121011011118.GF11890@momjian.us |
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Thread: | |
Lists: | pgsql-hackers |
On Wed, Oct 10, 2012 at 08:43:34PM -0400, Tom Lane wrote:
> > It seems to me that the
> > root of the issue here is that people is not that people expect two
> > snapshots -- indeed, a number of people strongly supported getting rid
> > of that behavior at the time -- but rather that they expect the
> > snapshot to be taken after locks are acquired.
>
> Sure. Maybe we can rejigger things in a way that does that, although
> I think the stumbling block is going to be parse-time calls to
> user-defined I/O functions for constants --- which might need a
> snapshot. It might be possible to redesign things so that all tables
> are locked before we do anything that requires a non-SnapshotNow
> snapshot, and then take a single "planning/execution" snapshot. But
> that is not this patch, and would be a lot more invasive than this
> patch, and would certainly not be back-patchable to 9.2.
>
> I think we have to revert and go back to the drawing board on this.
Is reverting going to adversely affect users who are already using the
9.2 behavior?
--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com
+ It's impossible for everything to be true. +
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