RE: Dead slow count(*)

From: Cary Millsap <cary.millsap_at_hotsos.com>
Date: Mon, 9 Feb 2004 12:52:11 -0600
Message-ID: <012f01c3ef3d$d6ee4990$6701a8c0@CVMLAP02>

I think Oracle will use an index to perform count(*) as well. ...If there exists an index with at least one NOT NULL column in its key.

In other words, I don't think you'll find a difference between the performance of count(*) and count(1). But try it. :)

(Thanks, Connor!)

Cary Millsap
Hotsos Enterprises, Ltd.
http://www.hotsos.com
* Nullius in verba *

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-----Original Message-----
From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Jonathan Redshaw Sent: Monday, February 09, 2004 12:16 PM To: oracle-l_at_freelists.org
Subject: RE: Dead slow count(*)

I received this tip in a PL/SQL class. On large table you can use count(1)
to force use of the index. I have not verified this but it may help.

>From: Jordi Adame V <jordi_at_inffinix.com>
>Reply-To: oracle-l_at_freelists.org
>To: Oracle-L_at_freelists.org
>Subject: Dead slow count(*)
>Date: Thu, 29 Jan 2004 17:54:46 -0600
>
>Hi!
>
>I have this table with ~4,000,000 entries
>
>When i do a SELECT COUNT(*) FROM TABLE_NAME
>
>it takes 4 hours to give me the result, this is way too much
>
>Im running Oracle 9.2.0.4.0 on RedHat AS 3
>
>These are my first experiences with Oracle, so I have no clue how to
fix
>this
>query time... Any help would be nice
>
>regards
>
>Jordi
>
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Received on Mon Feb 09 2004 - 12:52:11 CST