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Date: Thu, 3 Feb 2005 21:21:19 -0700
From: Michael Fuhr <mike@fuhr.org>
To: Don Drake <dondrake@gmail.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: Determining Rank
Message-ID: <20050204042119.GA64152@winnie.fuhr.org>
References: <6c21003b05020319061f8bce45@mail.gmail.com>
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On Thu, Feb 03, 2005 at 09:06:36PM -0600, Don Drake wrote:

> select some_val, count(*) 
> from big_table
> group by some_val
> order by count(*)
> limit 50
> 
> Now, I would like to have the rank included in the result set.  The
> first row would be 1, followed by 2, etc. all the way to 50.

Maybe use a temporary sequence?

CREATE TEMPORARY SEQUENCE rank_seq;

SELECT nextval('rank_seq') AS rank, *
FROM (SELECT some_val, count(*)
      FROM big_table
      GROUP BY some_val
      ORDER BY count(*)
      LIMIT 50) AS s;

DROP SEQUENCE rank_seq;

I don't know if row order is guaranteed to survive a subquery,
however.

-- 
Michael Fuhr
http://www.fuhr.org/~mfuhr/