RE: which should be faster

Thanks Jonathan,

I`ll spent some time testing.

Stephane Paquette
Administrateur de bases de donnees
Database Administrator
Standard Life
www.standardlife.ca
Tel. (514) 925-7187
stephane.paquette_at_standardlife.ca <mailto:stephane.paquette_at_standardlife.ca>

-----Original Message-----
Lewis
Sent: Monday, May 05, 2003 2:50 PM
To: Multiple recipients of list ORACLE-L

I suspect that this comment is highly
context-sensitive.

Oracle 9 can re-arrange the order of
filter predicates to reduce the estimated cost of a query.

Oracle 8 cannot.

Note - it is implicit in the software that the order of predicates can have an impact on the performance of a query, otherwise
there would be no need for the
/*+ ordered_predicates */ hint.
On the other hand, the order of the
(simple filter) predicates cannot affect the calculated cost of a query prior to
9i, because the calculated cost is
I/O based, not CPU based.

Regards

Jonathan Lewis
http://www.jlcomp.demon.co.uk

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• Original Message ----- To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com> Sent: 05 May 2003 16:52

> I've check on asktom and he is positive that the order of predicate
has no
> impact (DB version for that comment is 815).
> From the site :
>
> No, the order of evaluation of a predicate in SQL is purposely
> "indeterminate".
>

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