From: | "Josh Harrison" <joshques(at)gmail(dot)com> |
---|---|
To: | "Andrew Sullivan" <ajs(at)crankycanuck(dot)ca>, pgsql-general(at)postgresql(dot)org |
Subject: | Re: quick question abt pg_dump and restore |
Date: | 2008-01-09 16:51:16 |
Message-ID: | 8d89ea1d0801090851v8b777c0lcdfac4a2973af937@mail.gmail.com |
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Lists: | pgsql-general |
On Jan 9, 2008 11:39 AM, Andrew Sullivan <ajs(at)crankycanuck(dot)ca> wrote:
> On Wed, Jan 09, 2008 at 05:28:15PM +0100, Ivan Sergio Borgonovo wrote:
> > Does it make any sense *knowing* how the implementation works to load
> > records in a table in a specific order to improve performances?
>
> Well, this is more or less what CLUSTER does. There are some cases where
> happening to know about the order the table is in will yield happy
> effects,
> yes.
>
You are right. Sometimes when i cluster the table according to the
frequently accessed indexes then it makes queries pretty fast. But its not a
feasible solution always since some tables have more indexes which are
accessed frequently. So clustering the table according to one index will
yield poor performance to queries involving other indexes. Index-only scan
is a good solution for this I guess for queries involving indexed columns
(like in oracle) !!!
josh
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