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: | Pine.GSO.4.64.0701171856420.4471@kingcheetah.tanabi.org |
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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).
Steve
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