Re: Poor plan choice in prepared statement

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От bricklen
Тема Re: Poor plan choice in prepared statement
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Msg-id 33b743250812301511x30f1b377uf55fdca82d243c37@mail.gmail.com
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Ответ на Re: Poor plan choice in prepared statement  (Tom Lane <tgl@sss.pgh.pa.us>)
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Hi Tom,

On Tue, Dec 30, 2008 at 3:02 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> The point of a prepared statement IMHO is to do the planning only once.
> There's necessarily a tradeoff between that and having a plan that's
> perfectly adapted to specific parameter values.

I agree, and normally it wouldn't be an issue. In this particular
case, we are seeing response time to go from sub-second with
non-prepared queries, to over 200 seconds w/ prepared queries. Note
that is not an isolated case in our application, merely the numbers
from this particular example.

>
> Reasonable client-side APIs should provide the option to use out-of-line
> parameters, which is what you want to prevent SQL injection, without
> hard-wiring that to the orthogonal concept of statements whose plan is
> prepared in advance.  In libpq, for instance, PQexecParams() does that.
>
>                        regards, tom lane
>

Again, I agree completely. What I am after I guess are some pointers
on where to look for that, with regards to PHP. Whatever I turn up, I
will turn over to our developers, but before I do that I want to be
sure I am giving them the correct advice.

Thanks,

Bricklen

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