Re: visibility maps and heap_prune

From: Bruce Momjian <bruce(at)momjian(dot)us>
To: Pavan Deolasee <pavan(dot)deolasee(at)gmail(dot)com>
Cc: Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: visibility maps and heap_prune
Date: 2009-01-15 01:40:59
Message-ID: 200901150140.n0F1exD12180@momjian.us
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Is this something for 8.4 CVS?

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Pavan Deolasee wrote:
> On Mon, Dec 8, 2008 at 11:33 AM, Pavan Deolasee <pavan(dot)deolasee(at)gmail(dot)com>wrote:
>
> >
> >
> > On Sat, Dec 6, 2008 at 8:08 PM, Heikki Linnakangas <
> > heikki(dot)linnakangas(at)enterprisedb(dot)com> wrote:
> >
> >>
> >> If you see a straightforward way, please submit a patch!
> >>
> >>
> > Will do that.
> >
> >
>
> Here is a patch which implements this. The PD_ALL_VISIBLE flag is set if all
> tuples in the page are visible to all transactions and there are no DEAD
> line pointers in the page. The second check is required so that VACUUM takes
> up the page. We could slightly distinguish the two cases (one where the page
> requires vacuuming only because of DEAD line pointers and the other where
> the page-tuples do not require any visibility checks), but I thought its not
> worth the complexity.
>
> Thanks,
> Pavan
>
> --
> Pavan Deolasee
> EnterpriseDB http://www.enterprisedb.com

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Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

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