Hi,
after testing Joergs case and some other cases
(using version 10.00) I came to the comclusion that
1. Joerg is right. External directives dont work with
prepared statements
2. The whole external directives thing only works
if you are dealing with a statement that is 100%
the same every time you run it.
If your Application queries for lets say
SELECT * FROM sometable WHERE name='Joerg'
you will not be able to optimize the statement where
'Joerg' is exchanged with lets say a user input tomorrow.
If this is true external directives are not usable in
99,9% of the cases where you would like to use them.
.... i.e. the whole concept is good for (nearly) nothing -
something that sounded cool in the tech conferences
where I heard about it but fails when you try it.
Maybe I missed something here (or maybe it is doing
better in a version >10?). Could someone please
comment on this?
Regards,
Dirk
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--
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"Joerg Rueschenschmidt" <jrueschenschmidt@[EMAIL PROTECTED]
> schrieb im
Newsbeitrag news:g4q45i$msv$03$1@[EMAIL PROTECTED]
> Dirk Gunsthövel schrieb:
>> Hi,
>>
>> first you should be able to set the optimizer goal per session using
>> SET OPTIMIZATION FIRST_ROWS
>>
>> secondly how do you see that the optimizer hints (that is what you
>> mean, right?) are not used? Do you have any helpfull output?
>>
>> (I had to use optimizer hints with Informix only in some rare
>> occasions where the data structures where messed up and
>> had to stay like that for some 'good' reasons ;-) )
>>
>> Regards,
>> Dirk
>>
>
> Dirk,
>
> I need to set the goal for a single query only. The overall goal
ALL_ROWS
> is okay.
>
> Further, I think SET OPTIMIZATION requires access to the source code of
> the third party product, which does not exist. Assume I could change
> optimization goal for a database session from outside. It would not
help,
> because the third party product open and close database sessions
> dynamicly. I would never now what database session will run my "bad"
> query.
>
> Fyi, a query execution plan will give you informations about if a
> directive is used or not.
>
> Regards ...
>
> Joerg
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