uhh... thats not exactly true. oracle is a bastardization of set theory. there are alot of cases where 'not exists' and 'not in'(if doing a hash anti-join' are much superior to minus.
here are some generalizations. 1. not in with a hash_aj is the best if -- your sub-query is significantly less 'costly' then your out query... that is NOT based on the 'cost' of the explain plain. 2. If they are about the same or the out is more costly, go with not exists. 3. If you need to do a large full tablescan or if the outer query is very small relative to the inner query, minus tends to be the best. These are broad generalizations, but work well and are MUCH better than just guessing. > > From: Mladen Gogala <[EMAIL PROTECTED]> > Date: 2003/12/18 Thu AM 09:14:24 EST > To: Multiple recipients of list ORACLE-L <[EMAIL PROTECTED]> > Subject: Re: Any known problems using NOT IN ? > > Actually, because relational database conform to the rules of set theory, > I find it preferable to use "MINUS" wherever possible. Oracle optimizer > is trained to spot set operations and they usually generate sort/merge > or hash based execution plan, while "NOT IN" and "NOT EXIST" can generate > NL plan, which is, generally speaking, undesired when you do set operations. > > On 12/18/2003 12:39:26 AM, Charu Joshi wrote: > > Siddharth, > > > > The NOT IN query fails to return rows, if the inner sub-query returns NULL > > values. It is always recommended to use the NOT EXISTS clause, unless you > > are sure that the inner query will not return any NULLs. > > > > Regards, > > Charu. > > > > -----Original Message----- > > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of > > Siddharth Haldankar > > Sent: 18 December 2003 10:54 > > To: Multiple recipients of list ORACLE-L > > Subject: Any known problems using NOT IN ? > > > > Hi Gurus, > > > > I have a problem using NOT IN clause in Oracle. However using NOT EXISTS, > > gives me the right output. Are there any known limitations. > > > > This query selects from the master records wherein child records are not > > active. > > > > select * from ct_software_release csr where > > > > csr.class = 'NS' > > > > AND csr.active_flag = 'Y' > > > > AND csr.os_id_pk not IN > > > > (SELECT crs.os_id_fk1 FROM CT_ROADMAP_SOFTWARE crs > > > > WHERE crs.active_flag = 'Y'); > > > > The sub-query in the above case gives 1800 rows. The above query fails to > > give any rows. > > > > select * from ct_software_release csr where > > > > csr.class = 'NS' > > > > AND csr.active_flag = 'Y' > > > > AND NOT EXISTS > > > > (SELECT 1 FROM CT_ROADMAP_SOFTWARE crs > > > > WHERE crs.os_id_fk1 = csr.os_id_pk > > > > AND crs.active_flag = 'Y'); > > > > This above query works fine. > > > > Thanks > > > > ---------------------------------------------------------------------------- > > -- > > > > Siddharth Haldankar > > > > Zensar Technologies Ltd. > > > > Cisco Systems Inc. > > > > (Offshore Development Center) > > > > # : 091 020 4128394 > > > > [EMAIL PROTECTED] > > > > [EMAIL PROTECTED] > > > > ********************************************************* > > Disclaimer > > > > This message (including any attachments) contains > > confidential information intended for a specific > > individual and purpose, and is protected by law. > > If you are not the intended recipient, you should > > delete this message and are hereby notified that > > any disclosure, copying, or distribution of this > > message, or the taking of any action based on it, > > is strictly prohibited. > > > > ********************************************************* > > > > Visit us at http://www.mahindrabt.com > > > > > > -- > Mladen Gogala > Oracle DBA > -- > Please see the official ORACLE-L FAQ: http://www.orafaq.net > -- > Author: Mladen Gogala > INET: [EMAIL PROTECTED] > > 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: [EMAIL PROTECTED] (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). > -- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: <[EMAIL PROTECTED] INET: [EMAIL PROTECTED] 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: [EMAIL PROTECTED] (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).
