Re: Lazy Snapshots

From: "simon(at)2ndquadrant(dot)com" <simon(at)2ndquadrant(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: PG Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Lazy Snapshots
Date: 2009-08-21 18:41:30
Message-ID: 316903078.9934.1250880090693.JavaMail.open-xchange@oxltgw02.schlund.de
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On 18 August 2009 at 16:18 Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> Simon, this concept is completely broken, as far as I can tell.

Thanks for the precise example.

Yes, I agree it is not going to work when there could be more than one row
version in the relation. Which doesn't leave useful wriggle room, so not
pursuing this further.

What a shame.

As discussed on -perform, it does seem as if we might have retrospectively
calculated snapshots if we had the right data structure. But that's a different
set of thoughts for another day.

Best Regards, Simon Riggs

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