I think Waleed's point is that he is yet to see an
example where such an optimization has taken place.
cheers
connor
- Kevin Toepke <ktoepke_at_rlcarriers.com> wrote: >
One of the optimizations behind the DETERMINISTIC
> keyword is that Oracle
> caches previously computed values. If you pass the
> same values into the
> function twice, the function body will execute at
> least once and at most
> twice. You can NOT count on the function body being
> executed for each call.
>
> This is actually a cool feature. Consider a
> situation where you are
> repeatedly performing time-consuming
> computations/lookups. If Oracle caches
> previously computed values for you, this can lead to
> significant performance
> benefits!
>
> Kevin T
>
> -----Original Message-----
> Sent: Friday, October 03, 2003 9:51 AM
> To: Multiple recipients of list ORACLE-L
>
>
> As far as I know, with all current releases of
> Oracle,
> determinism is purely for function based indexes.
> The
> deterministic keyword indicates that the function
> values when you created the index are still
> preserved
> when you query it.
>
> Thus the "first" execution was during index
> creation,
> and the "second" execution is during subsequent
> queries during which the function does not need to
> be
> executed because it is deterministic.
>
> (Lame eh?)
>
>
>
> --- "Khedr, Waleed" <Waleed.Khedr_at_FMR.COM> wrote: >
> drop table test_det;
> > create table test_det (c1 date);
> > create or replace function f2 (p1 in number, p2 in
> > number) return number
> > deterministic is
> > pragma autonomous_transaction;
> > begin
> > insert into test_det values (sysdate);
> > commit;
> > return(p1 * p2);
> > end;
> > /
> > select f2 (1,3) from dual where f2 (1,3) = 3;
> > F2(1,3)
> > ----------
> > 3
> > select * from test_det;
> > C1
> > ---------
> > 02-OCT-03
> > 02-OCT-03
> > It did not save an execution even in the same sql
> > call!
> > Oracle 9.2.0.2 Solaris 2.8
> > Regards,
> >
> > Waleed
> >
> > --
> > Please see the official ORACLE-L FAQ:
> > http://www.orafaq.net
> > --
> > Author: Khedr, Waleed
> > INET: Waleed.Khedr_at_FMR.COM
> >
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> =====
> Connor McDonald
> web: http://www.oracledba.co.uk
> web: http://www.oaktable.net
> email: connor_mcdonald_at_yahoo.com
>
> "GIVE a man a fish and he will eat for a day. But
> TEACH him how to fish,
> and...he will sit in a boat and drink beer all day"
>
>
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> Author: =?iso-8859-1?q?Connor=20McDonald?=
> INET: hamcdc_at_yahoo.co.uk
>
> Fat City Network Services -- 858-538-5051
> http://www.fatcity.com
> San Diego, California -- Mailing list and web
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> To REMOVE yourself from this mailing list, send an
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>
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Connor McDonald
web:
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web:
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email: connor_mcdonald_at_yahoo.com
"GIVE a man a fish and he will eat for a day. But TEACH him how to fish, and...he will sit in a boat and drink beer all day"
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Received on Fri Oct 03 2003 - 23:59:25 CDT
