Re: Exact index overhead

From: "Scott Marlowe" <scott(dot)marlowe(at)gmail(dot)com>
To: "Gunther Mayer" <gunther(dot)mayer(at)googlemail(dot)com>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Exact index overhead
Date: 2008-04-19 16:48:42
Message-ID: dcc563d10804190948o573612d0r51e3792574962b99@mail.gmail.com
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On Thu, Apr 17, 2008 at 9:42 AM, Gunther Mayer
<gunther(dot)mayer(at)googlemail(dot)com> wrote:
> Pavan Deolasee wrote:
>

> > 2. The existing block should have enough free space to accommodate the
> > new version
> > A less than 100 fillfactor may help you given your rate of updates.
> >
> >
> I see, as soon as a new block is required for the new version the index
> pointer needs updating too, I understand now. But at least in the common
> case of space being available the index overhead is reduced to zero. I can
> live with that.

Quick clarification, it's the table, not the index that has to have
free space for the new row version. This rewards good normalization
practices (narrower rows) and a lower fill factor.

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