| Oracle FAQ | Your Portal to the Oracle Knowledge Grid | |
 |
 | |||
| Oracle FAQ | Your Portal to the Oracle Knowledge Grid | |
|
| |||
Home -> Community -> Mailing Lists -> Oracle-L -> RE: slowish query causing problems...
Eva,
Is there an index on the fwepcode1 table with the three columns used in the where clause? Are the three columns varchar or varchar2? Make sure the EXP column is not a number!
Secondly, I think I would change the query as follows:
SELECT DISTINCT (1)
FROM fwepcode1
WHERE (wotype = 'TST' AND func = 'C0NEPRF' AND EXP = '22222')
OR not exists(select 1 FROM valuelist
WHERE listname = 'STATUS'
AND MAXVALUE = 'AAAAA'
AND VALUE='INPRG' )
Tom Mercadante
Oracle Certified Professional
-----Original Message-----
Sent: Tuesday, January 14, 2003 6:29 AM
To: Multiple recipients of list ORACLE-L
Hello List,
Pls help me on this problem. Our application does a validation when it uses a certain screen, as it so happens this screen is used very intensively. The performance is very slow, I have isolated the main culprit. I have tried the following.
I have dropped all the indexes and tried recreating them individually. Each time I have run an explain plan on the query, the optimizer (both rule and Choose) have chosen to do a FULL table scan on the fwepcode table. Even when using a hint to explicitly use the index it still uses FULL.
This is very frustrating indeed.
SELECT DISTINCT (1)
FROM fwepcode1
WHERE (wotype = 'TST' AND func = 'C0NEPRF' AND EXP = '22222')
OR 'INPRG' NOT IN (SELECT VALUE
FROM valuelist
WHERE listname = 'STATUS'
AND MAXVALUE = 'AAAAA')
Is the reason that the optimizer does not use any of the indexes because of
the SELECT DISTINCT (1)?
I have tried adjusting this query slightly to remove this and it still
insists on doing a full table scan.
Funny enough the sub query on valuelist table does use a index.
The table contains 8920 rows. The cost according to the explain plan is 703
and bytes 9834.
The system is a Oracle 817 on Win2k.
Pls advise, any options or help will be appreciated.
Many Thanks
Denham Eva
Oracle DBA
"UNIX is basically a simple operating system, but you have to be a genius to
understand the simplicity."
Dennis Ritchie.
DISCLAIMER This message is for the named person's use only. It may contain confidential, proprietary or legally privileged information. No confidentiality or privilege is waived or lost by any mistransmission. If you receive this message in error, please immediately delete it and all copies of it from your system, destroy any hard copies of it and notify the sender. You must not, directly or indirectly, use, disclose, distribute, print, or copy any part of this message if you are not the intended recipient. TFMC, its holding company, and any of its subsidiaries each reserve the right to monitor and manage all e-mail communications through its networks.
Any views expressed in this message are those of the individual sender, except where the message states otherwise and the sender is authorized to state them to be views of any such entity.
This e-mail message has been scanned for Viruses and Content and cleared by MailMarshal - For more information please visit <http://www.marshalsoftware.com> www.marshalsoftware.com
-- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Mercadante, Thomas F INET: NDATFM_at_labor.state.ny.us 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 Tue Jan 14 2003 - 07:24:11 CST
 |
 |