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Re: Configuration Advice

From: Steve <cheetah(at)tanabi(dot)org>
To: Bruno Wolff III <bruno(at)wolff(dot)to>
Cc: Adam Rich <adam(dot)r(at)sbcglobal(dot)net>, pgsql-performance(at)postgresql(dot)org
Subject: Re: Configuration Advice
Date: 2007-01-17 23:58:52
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-performance
> Note that you only need to have the ASC and DESC versions of opclasses when
> you are going to use multicolumn indexes with some columns in ASC order and
> some in DESC order. For columns used by themselves in an index, you don't
> need to do this, no matter which order you are sorting on.

Yeah, I assumed the people 'in the know' on this kind of stuff would know 
the details of why I have to have those, and therefore I wouldn't have to 
go into detail as to why -- but you put your finger right on it. :) 
Unfortunately the customer this is for wants certain columns joined at the 
hip for querying and sorting, and this method was a performance godsend 
when we implemented it (with a C .so library, not using SQL in our 
opclasses or anything like that).


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