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Home -> Community -> Mailing Lists -> Oracle-L -> RE: Driving table
First question is whether you're in Cost Based or Rule Based optimization. In RBO you are correct that it will read tables right to left unless instructed otherwise by a hint.
In CBO, Oracle will choose what it thinks is 'best', which most of the time, but not all of the time :), will be true.
Jay Miller
-----Original Message-----
Sent: Friday, April 06, 2001 6:45 AM
To: Multiple recipients of list ORACLE-L
Hi friends ,
I have got some query regarding , how the query is exactly executed ??
We always take joins and if we see the plan of the query , there is always
one
main driving table . Some times I get feeling that , in the join the right
most table is the driving table . But that is not always true , this is my
observation from several plans .
In Oracle documentation alos ita mentioned that ( Server Concepts, 815 or
816
: Optimisation of Joins ), "one driving table is selected" , but at least I
cannot makeout which of the several tables will be selected as driving table
.
What can be the potential criterions of selecting a driving table ?
Please , if you all can throw some light on the same or can redirect to some document , that would be great .
Cheers ,
Anup Saxena
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Author:
INET: A.SAXENA_at_ponl.com
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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 Fri Apr 06 2001 - 11:41:05 CDT
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