Re: Pre-allocated free space for row

From: Simon Riggs <simon(at)2ndquadrant(dot)com>
To: Satoshi Nagayasu <nagayasus(at)nttdata(dot)co(dot)jp>
Cc: josh(at)agliodbs(dot)com, pgsql-hackers(at)postgresql(dot)org, "Jim C(dot) Nasby" <jnasby(at)pervasive(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Subject: Re: Pre-allocated free space for row
Date: 2005-08-31 21:07:04
Message-ID: 1125522424.3956.4.camel@localhost.localdomain
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On Wed, 2005-08-31 at 16:50 +0900, Satoshi Nagayasu wrote:
> Simon Riggs wrote:
> >>4. Allow to repair fragmentation in each page.
> >>
> >>Because updates cause fragmentation in the page.
> >>
> >>So we need to keep large continuous free space in each page,
> >>if we want to get more effective on PCTFREE feature.
> >
> >
> > ...doesn't VACUUM already do that?
>
> VACUUM generates a huge load because it repaires all pages
> on the table file.
>
> I think (more light-weight) repairing on a single page
> is needed to maintain free space in the specific page.

So PCTFREE is an OK idea, but lets drop #4, which is a separate idea and
not one that has gained agreeable consensus.

Best Regards, Simon Riggs

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