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Re: planner/optimizer question

From: Manfred Koizar <mkoi-pg(at)aon(dot)at>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: "Gary Doades" <gpd(at)gpdnet(dot)co(dot)uk>,pgsql-performance(at)postgresql(dot)org
Subject: Re: planner/optimizer question
Date: 2004-04-29 17:03:03
Message-ID: pvc290584alms4s6hurvsh5ra09ki7se1s@email.aon.at (view raw or flat)
Thread:
Lists: pgsql-performance
On Wed, 28 Apr 2004 09:05:04 -0400, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> [ ... visibility information in index tuples ... ]

>Storing that information would at least double the overhead space used
>for each index tuple.  The resulting index bloat would significantly
>slow index operations by requiring more I/O.  So it's far from clear
>that this would be a win, even for those who care only about select
>speed.

While the storage overhead could be reduced to 1 bit (not a joke) we'd
still have the I/O overhead of locating and updating index tuples for
every heap tuple deleted/updated.

Servus
 Manfred

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