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Date: Wed, 30 May 2007 10:03:16 -0700 (PDT)
From: Trigve Siver <trigves@yahoo.com>
Subject: Re: slow query execution
To: pgsql-sql@postgresql.org
MIME-Version: 1.0
Content-Type: text/plain; charset=ascii
Message-ID: <710412.41081.qm@web52709.mail.re2.yahoo.com>

Hi, 
Thanks for reply, As you have mentioned I need to get row numbers for my query, so when I make some other query with same data I will know which row number has a particular ID. As you mentioned "You can
do this with a temporary sequence, among other approaches...". Can you point me to some sources or give me some examples, please?

Thanks 

Trigve

----- Original Message ----
From: Andrew Sullivan <ajs@crankycanuck.ca>
To: pgsql-sql@postgresql.org
Sent: Wednesday, May 30, 2007 6:45:53 PM
Subject: Re: [SQL] slow query execution

On Wed, May 30, 2007 at 08:56:45AM -0700, Trigve Siver wrote:
> Hi all,
> 
> This query executes very slow:
> 
> select (select count(*) from customer where id <= a.id) as row, id,
> from customer as a order by id;

So you are trying to get the ordinal position of every ID in the
table?  I'm not surprised it takes a long time -- you have to join
the whole table to itself and then do a lot of counting.  Are you
just trying to get the "row number" for your query answer?  You can
do this with a temporary sequence, among other approaches, more
cheaply.

A


-- 
Andrew Sullivan  | ajs@crankycanuck.ca
Users never remark, "Wow, this software may be buggy and hard 
to use, but at least there is a lot of code underneath."
        --Damien Katz

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