sSQL = "update itemloc set
average_cost =" & costo & " where (company='2000') and item= '" &
Arti & "'"
and she told me that per item it
takes like 10 seconds.
After read the article that I mention
she changes the statement to this :
sSQL = "update /*+
INDEX(itemloc ITLSET2) */ itemloc set average_cost =" & costo & "
where (company='2000') and item= '" & Arti & "'"
ITLSET2 is a index that have company(1),
location(2) and Item(3) and it takes 2
seconds per item, so that is way she is convinced that we have to uses the
/*+ INDEX(itemloc ITLSET2) */ in all of our select, update or
delete statement.
I hope you undestant my English and my problem
too, because I have to do some really complicated queries that have
like 3 or 5 tables in them, and using this method will give me some
serious complications, maybe in this case (change of the average cost) is not
too dangerous.
But I have to give her strong statements
to change her mind.
Thanks for everything
friends!!
>>> [EMAIL PROTECTED] 06/25/03 06:10PM
>>>
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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