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Re: Updated bitmap index patch

From: Andrew Dunstan <andrew(at)dunslane(dot)net>
To: Gavin Sherry <swm(at)alcove(dot)com(dot)au>
Cc: pgsql-patches(at)postgresql(dot)org
Subject: Re: Updated bitmap index patch
Date: 2007-06-01 14:38:48
Message-ID: 46602F78.9050502@dunslane.net (view raw or flat)
Thread:
Lists: pgsql-hackerspgsql-patches

Gavin Sherry wrote:
> Hi all,
>
> Attached is an updated bitmap index patch. It contains bug fixes, API
> changes, binary changes (page identifier to distinguish it from other
> indexes) and has been brought up to HEAD.
>
> I worked on a few approaches to VACUUM, none very satisfactory. The
> problem is, breaking a compressed word representing matches can have
> serious consequences -- at the least, creation of new words, at the worst,
> creation of a new page. If a lot of this were to happen, REINDEX would be
> much more efficient (this is what earlier patches did).
>
> One approach I looked at was modifying the existing read API to be able to
> do something like "kill prior tuple". This, I think, made the API quite
> complex and it was hard to implement, since the existing mechanism
> decompresses words on the fly and it would be hard to identify which TID
> is no longer a match. So, I dropped this idea pretty quickly.
>
> The second approach is to just manually traverse each vector and change
> matches to non-matches where necessary. The complexity then is in managing
> the consequences of breaking compressed words, doing WAL (efficiently) and
> calculating free space. I've only partially implemented this approach. At
> this stage, I don't have time to finish it due to other commitments.
>
>   
>

What exactly is the state of this patch? Reading this email it looks to 
me like something that should wait for 8.4. Or is there some part of it 
that is ready for 8.3? If so, which part?

cheers

andrew

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