Oracle FAQ Your Portal to the Oracle Knowledge Grid
HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US
 

Home -> Community -> Mailing Lists -> Oracle-L -> Re: minus vs. where not exists, vs. where not in

Re: minus vs. where not exists, vs. where not in

From: Wolfgang Breitling <breitliw_at_centrexcc.com>
Date: Sun, 21 Sep 2003 11:24:35 -0800
Message-ID: <F001.005D09FE.20030921112435@fatcity.com>


First off, the three are not equivalent, not substitutes for each other. Well not in and minus would be, but they are different from not exists. "not in"/"minus" and "not exists" can return different results. See <http://asktom.oracle.com/pls/ask/f?p=4950:8:::::F4950_P8_DISPLAYID:442029737684>http://asktom.oracle.com/pls/ask/f?p=4950:8:::::F4950_P8_DISPLAYID:442029737684

for examples and explanation.

I have not done any performance comparisons but I personally routinely use minus and I am quite happy with it, especially across a db link.

At 09:59 AM 9/21/2003 -0800, you wrote:
>Do any of you have any cases when minus is superior in performance? Ive
>found 'not in' with a hash_aj to be the best option if the sub-query is
>significantly less 'costly' then the outer query. I dont mean cost in
>terms of the Explain Plan, I mean the work Oracle has to do to find a
>result set. It also depends on a proper hash_area_size
>
>I find 'where not exists' to be best if the subquery is relatively close
>in cost to the outer query. Yes I know you cant make broad
>generalizations, but there has to be some 'narrow' generalizations you can
>make. Such as certain cases, etc...
>
>what have you seen? There seems to be very little work in this area in the
>literature.
>
>Does 'where not exist' need more or less sort_area_size space than minus?

Wolfgang Breitling
Oracle7, 8, 8i, 9i OCP DBA
Centrex Consulting Corporation
http://www.centrexcc.com

-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.net
-- 
Author: Wolfgang Breitling
  INET: breitliw_at_centrexcc.com

Fat City Network Services    -- 858-538-5051 http://www.fatcity.com
San Diego, California        -- Mailing list and web hosting services
---------------------------------------------------------------------
To REMOVE yourself from this mailing list, send an E-Mail message
to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in
the message BODY, include a line containing: UNSUB ORACLE-L
(or the name of mailing list you want to be removed from).  You may
also send the HELP command for other information (like subscribing).
Received on Sun Sep 21 2003 - 14:24:35 CDT

Original text of this message

HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US