Re: Pre-allocated free space for row updating (like PCTFREE)

From: Satoshi Nagayasu <nagayasus(at)nttdata(dot)co(dot)jp>
To: Simon Riggs <simon(at)2ndquadrant(dot)com>
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 updating (like PCTFREE)
Date: 2005-08-30 23:32:12
Message-ID: 4314EC7C.10903@nttdata.co.jp
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Simon Riggs wrote:
> The summary was:
>
> 1. Have a PCTFREE column added on a table by table basis

I think a good place to keep PCTFREE value is a new column
in the pg_class, and ALTER TABLE should be able to change this value.

> 2. Apply PCTFREE for Inserts only
> 3. Allow Updates to use the full space in the block.

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.

--
NAGAYASU Satoshi <nagayasus(at)nttdata(dot)co(dot)jp>

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