Ethan,
A NOT EXISTS can be very expensive if returning large numbers
of rows from the driving table. It's a correlated subquery as
Stephane F. pointed out in another post.
Jared
"Post, Ethan" <[EMAIL PROTECTED]>
Sent by: [EMAIL PROTECTED]
11/15/2002 10:32 AM
Please respond to ORACLE-L
To: Multiple recipients of list ORACLE-L <[EMAIL PROTECTED]>
cc:
Subject: RE: RE: RE: CONSISTANT GETS
Hold the press. NOT IN better than NOT EXISTS? Is this theory or fact?
If
so is there any supporting evidence out there? This is the first I have
heard of this.
Thanks!
-----Original Message-----
Sent: Friday, November 15, 2002 11:35 AM
To: Multiple recipients of list ORACLE-L
Jerry,
I suspect that the improvments are more likely due to your
rewriting the WHERE clause rather than the use of NOT EXISTS.
Especially if the database were 9i, where NOT IN actually
seems get a better execution path than NOT EXISTS.
That original WHERE clause is really a piece of work.
Jared
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