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Re: multicolumn index column order

From: valgog <valgog(at)gmail(dot)com>
To: pgsql-performance(at)postgresql(dot)org
Subject: Re: multicolumn index column order
Date: 2007-07-25 08:34:00
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Lists: pgsql-performance
On Jul 25, 2:14 am, Lew <l(dot)(dot)(dot)(at)lewscanon(dot)nospam> wrote:
> How about two indexes, one on each column?  Then the indexes will cooperate
> when combined in a WHERE clause.
> <>
> I don't believe the index makes a semantic difference with regard to ascending
> or descending.  An index is used to locate records in the selection phase of a
> query or modification command.
> --
> Lew

Ordered indexes (b-tree in this case) are also used to get the needed
record order and it is absolutely not necessary to have a WHARE clause
in your select statement to use them when you are using ORDER BY.


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