Re: Idea for getting rid of VACUUM FREEZE on cold pages

From: Simon Riggs <simon(at)2ndQuadrant(dot)com>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Jan Wieck <JanWieck(at)yahoo(dot)com>, Alvaro Herrera <alvherre(at)commandprompt(dot)com>, Russell Smith <mr-russ(at)pws(dot)com(dot)au>, Josh Berkus <josh(at)agliodbs(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Idea for getting rid of VACUUM FREEZE on cold pages
Date: 2010-06-08 22:18:26
Message-ID: 1276035506.12489.4314.camel@ebony
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On Tue, 2010-06-08 at 18:03 -0400, Robert Haas wrote:
> OK, yes, I see what you're getting at now. There are two possible
> ways to do freeze the tuples and keep the xmin: we can either rely on
> the PD_ALL_VISIBLE page-level bit (as I previously proposed) or we can
> additionally have a HEAP_XMIN_FROZEN bit as you propose here. I am
> not sure which way is better.

Doing it at tuple level is more flexible and allows more aggressive
freezing. It also works better with existing tuple visibility code.

--
Simon Riggs www.2ndQuadrant.com

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