Teresita,
I don't fully understand whether adding or removing a hint caused the
problem but like Stephane said - you should probably stay away from them
for now. If adding a hint decreased performance then you have proved this
for yourself.
A couple of important points:
* Using an index isn't always faster than scanning the table
* If a database is correctly analyzed then the optimisor can determine when
to use indexes or not automatically
* Hints can force the optimisor to choose a non-optimal execution plan. If
you are smarter than the optimisor this may be fine but in most cases the
optimisor will make the right decision when all tables are analyzed
* Hints have very specific formatting and object name rules. If you rename
an index the hint will become invalid and be blissfully ignored - you won't
even know.
* There are some hints which can safely be used but it takes a good
understanding of Oracle first. My advice would be don't use them. If you
have a specific problem then post lot's of details here and someone might
suggest trying a hint.
* Until you really understand the implications of using a specific hint it
can be dangerous in terms of performance - Stephane is not lying when he
says you can do more harm than good. I have many cases where I can "tune"
a query simply by removing the hints which someone included and letting
Oracle do what it does best.
Regards,
Mark.
"Teresita Castro"
<[EMAIL PROTECTED] To: Multiple recipients of list
ORACLE-L <[EMAIL PROTECTED]>
martmx.com> cc:
Sent by: Subject: Re: Index question
[EMAIL PROTECTED]
om
26/06/2003 09:29
Please respond to
ORACLE-L
Ophss...I have a terrible problem, I am using VB with Oracle and since we
put that instruccion on the execute instruction our execution time
decrease.
The problem is that my boss was the one that found that instruction and I
have to told her not to uses it, but with her I have to show some evidence
that show why now to uses hits.
Do you have any information that I can show to her.
Thanks!!!
>>> [EMAIL PROTECTED] 06/25/03 02:34PM >>>
Teresita,
Since you advertise yourself as a newbie, listen to an old-timer :
for the next two years, forget about hints. You risk doing more harm
than good.
--
Regards,
Stephane Faroult
Oriole Software
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