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Subject: Re: Need help in setting optimal configuration for a huge
From: Tomasz Rybak <bogomips@post.pl>
To: "Craig A. James" <cjames@modgraph-usa.com>
Cc: Kishore B <kishorebh@gmail.com>, pgsql-performance@postgresql.org
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References: <42567e060510221415r2516523l4c3f9b42dee91a09@mail.gmail.com>
	<435BBAF0.8080500@modgraph-usa.com>
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Date: Sun, 23 Oct 2005 19:17:56 +0200
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Dnia 23-10-2005, nie o godzinie 09:31 -0700, Craig A. James napisał(a):
<cut>
> MIN() and MAX() -- These are surprisingly slow, because they seem to do a full table scan EVEN ON AN INDEXED COLUMN!
In 8.1 this is no true, see the changelog.

> I don't understand why, but happily there is an effective substitute:
> 
>    select mycolumn from mytable order by mycolumn limit 1;  -- same as MIN()
> 
>    select mycolumn from mytable order by mycolumn desc limit 1;  -- same as MAX()

In 8.1 these queries are equivalent:

select mycolumn from mytable order by mycolumn limit 1;
select min(mycolumn) from mytable;

-- 
Tomasz Rybak <bogomips@post.pl>