Re: wholly / partially table read into shared buffer

From: Simon Riggs <simon(at)2ndquadrant(dot)com>
To: Григорий Титов <nav73(at)narod(dot)ru>
Cc: pgsql-admin(at)postgresql(dot)org
Subject: Re: wholly / partially table read into shared buffer
Date: 2007-09-24 21:59:45
Message-ID: 1190671185.4181.236.camel@ebony.site
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On Thu, 2007-09-20 at 19:07 +0400, Григорий Титов wrote:

> I am newbie in Postgres, but previously worked with Oracle. Now I am
> puzzled with heap_blks_hit/heap_blks_read ratio. I make select from
> table (whose size is larger than shared_buffer) and saw that it was
> wholly read from disk after second, third and so on runs. Isn't is
> wrong that RDBMS tries to cache table data blocks at least PARTIALLY
> in the case of insufficient cache buffer?

It does cache partially, but its always the wrong part of the table.

BTQ, Oracle does that too...

--
Simon Riggs
2ndQuadrant http://www.2ndQuadrant.com

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