Re: [PATCHES] Big number of "unused" pages as reported by

From: "Zeugswetter Andreas SB SD" <ZeugswetterA(at)spardat(dot)at>
To: "Yury Bokhoncovich" <byg(at)center-f1(dot)ru>, "Christopher Kings-Lynne" <chriskl(at)familyhealth(dot)com(dot)au>
Cc: "Hackers" <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: [PATCHES] Big number of "unused" pages as reported by
Date: 2002-09-06 07:33:03
Message-ID: 46C15C39FEB2C44BA555E356FBCD6FA4961E76@m0114.s-mxs.net
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> I make a guess I've got this due to parallel running of a program making
> bulk INSERTs/UPDATEs into that table. Mmm...I need a way to avoid the big
> number of unused pages in such a case. LOCK TABLE?

Only UPDATEs and DELETEs (and rolled back INSERTs) cause unused pages.
The trick for other people was to run very frequent 'VACUUM goods;'
(like every 15 seconds) on tables when relatively few rows (in small tables)
where constantly beeing updated (e.g. counters/balances).

It might be sufficient in your case though to do the 'VACUUM goods;' after
every bulk UPDATE, like Christopher suggested. A concurrent vacuum won't
help if each bulk update is done in one single transaction.

Andreas

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