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Home -> Community -> Mailing Lists -> Oracle-L -> RE: Qualifying columns to improve performance?
Hi Arn,
There may be good reasons for explicitly qualifying all column references, but performance is not one of them, at least under Oracle 8i. I've just done some tests and there is absolutely no difference in the number of dictionary cache gets required during the parse, and no measurable difference in CPU usage.
I too remember being taught this back in version 6 days, and it is in the Gurry and Corrigan "Oracle Performance Tuning" book (2nd edition, page 138) so there may have been some validity to it in the past.
@ Regards,
@ Steve Adams
@ http://www.ixora.com.au/
@ http://www.christianity.net.au/
-----Original Message-----
Sent: Tuesday, 3 April 2001 12:30
To: Multiple recipients of list ORACLE-L
At a course some years ago, we were told that in join statements, we should qualify ALL our column names with the appropriate table name, not just those that may be ambiguous. The reason was that the parser would not need to spend time checking multiple tables to determine the table to which each column belongs.
Is this still a valid rule?
-- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Steve Adams INET: steve.adams_at_ixora.com.au Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Lists -------------------------------------------------------------------- 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 Apr 03 2001 - 10:24:01 CDT
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