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Home -> Community -> Mailing Lists -> Oracle-L -> RE: slowish query causing problems...
Ouch! I hate to see queries written this way...the query should answer the
question you are trying to ask. It appears you are checking for the
existance of a record in fwepcode1 that matches the criteria.
If I understand the query correctly, you want to return 1 row if one of 2 conditions is met.
My suggestion for rewriting the query is below.
Kevin
SELECT 1
FROM fwepcode1
WHERE wotype = 'TST' AND func = 'C0NEPRF' AND EXP = '22222' AND rownum = 1
SELECT 1
FROM valuelist
WHERE listname = 'STATUS'
AND maxvalue = 'AAAAA'
AND value = 'INPRG')
)l
-----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.
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-- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: Toepke, Kevin M INET: ktoepke_at_trilegiant.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 Tue Jan 14 2003 - 06:53:56 CST
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