Re: Fwd: [JDBC] Re: 9.4-1207 behaves differently with server side prepared statements compared to 9.2-1102 - Mailing list pgsql-hackers

From Marko Tiikkaja
Subject Re: Fwd: [JDBC] Re: 9.4-1207 behaves differently with server side prepared statements compared to 9.2-1102
Date
Msg-id 56965579.1020909@joh.to
Whole thread Raw
In response to Re: Fwd: [JDBC] Re: 9.4-1207 behaves differently with server side prepared statements compared to 9.2-1102  (Vladimir Sitnikov <sitnikov.vladimir@gmail.com>)
Responses Re: Fwd: [JDBC] Re: 9.4-1207 behaves differently with server side prepared statements compared to 9.2-1102  (Vladimir Sitnikov <sitnikov.vladimir@gmail.com>)
List pgsql-hackers
On 13/01/16 14:36, Vladimir Sitnikov wrote:
>> Say you already have a plan which looks like this:
>> Now the plan gets invoked with  $1 = 5.  What exactly in your mind would happen here?
>
> A sequential scan with $1=5 condition. What else could be there?

I don't know, it's your proposal :-)  But it looks like I misunderstood.

> Note: I do not suggest changing already cached plans yet.
> I suggest looking into "6th bind values" when building a cached plan.

But that wouldn't have helped your case.  The custom plan is *more 
expensive*; I'm guessing because the generic plan gambles on a better 
average case instead of preparing for the worst case.


.m



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