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Re: vacuum, performance, and MVCC

From: Bruce Momjian <bruce(at)momjian(dot)us>
To: PFC <lists(at)peufeu(dot)com>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: vacuum, performance, and MVCC
Date: 2006-06-27 16:18:23
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-hackers
PFC wrote:
> > My idea is that if an UPDATE places the new tuple on the same page as
> > the old tuple, it will not create new index entries for any indexes
> > where the key doesn't change.
> 	Basically the idea behind preventing index bloat by updates is to have  
> one index tuple point to several actual tuples having the same value.

The idea is not to avoid index bloat, but to allow heap reuse, and having
one index entry for multiple versions of an UPDATEd row is merely an
implementation detail.

  Bruce Momjian   bruce(at)momjian(dot)us

  + If your life is a hard drive, Christ can be your backup. +

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