On that line, I've just had a note from Gaja
about my commentary on the line:
"Rewrite all correlated subqueries using in-line views".
He was concerned that I may not think the
advice valid. So let me say quite categorically
that the comment was not a criticism of the
technique.
Converting a subquery into a join is a strategy
which will very often result in significant performance
benefits and Gaja is, I think, the first person I
have seen make a very special mention of it in
a public paper. (No doubt someone will correct
me on that quite soon).
My point was that although it is not the automatic,
the only, or even necessarily the correct solution
to the sight of a correlated subquery, Gaja's paper
will, one day, be quoted as the definitive proof
that you should ALWAYS do it. And such is the
stuff of the urban legend.
Jonathan Lewis
http://www.jlcomp.demon.co.uk
Next Seminar - UK, April 3rd - 5th
http://www.jlcomp.demon.co.uk/seminar.html
Host to The Co-Operative Oracle Users' FAQ
http://www.jlcomp.demon.co.uk/faq/ind_faq.html
Author of:
Practical Oracle 8i: Building Efficient Databases
-----Original Message-----
To: Multiple recipients of list ORACLE-L <[EMAIL PROTECTED]>
Date: 16 March 2002 09:27
|
|You're cheating. Most advice containing 'always', even only once,
stands
|a big chance of becoming a legend very soon.
|--
|Regards,
|
|Stephane Faroult
|Oriole Ltd
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Author: Jonathan Lewis
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