| From: | Oliver Jowett <oliver(at)opencloud(dot)com> |
|---|---|
| To: | John Lister <john(dot)lister(at)kickstone(dot)com> |
| Cc: | Dave Cramer <pg(at)fastcrypt(dot)com>, Péter Kovács <maxottovonstirlitz(at)gmail(dot)com>, Frédérik Bilhaut <frederik(dot)bilhaut(at)noopsis(dot)fr>, pgsql-jdbc(at)postgresql(dot)org |
| Subject: | Re: Very strange performance decrease when reusing a PreparedStatement |
| Date: | 2009-05-03 23:28:23 |
| Message-ID: | 49FE2897.3020802@opencloud.com |
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| Lists: | pgsql-jdbc |
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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