Re: Very strange performance decrease when reusing a PreparedStatement

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От Oliver Jowett
Тема Re: Very strange performance decrease when reusing a PreparedStatement
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Msg-id 49FE2897.3020802@opencloud.com
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Ответ на Very strange performance decrease when reusing a PreparedStatement  (Frédérik Bilhaut <frederik.bilhaut@noopsis.fr>)
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John Lister wrote:

> However it seems that other optimisations can't be made for example it
> doesn't seem possible to tell the server that parameter 1 is always
> going to be an int and therefore it should be using index A. The current
> implementation may not use index A as it is unaware as to the type of
> the supplied parameter. Perhaps in this case the execution planner
> should pick the parameters for the most optimal plan and return the
> types during the parse and let the driver convert the data to what the
> server requires...

No it's not a problem with types at all, parameter types are fixed at
the point the named statement is created.

It's all about index selectivity statistics.

-O

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