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Re: performance issue

From: Oliver Jowett <oliver(at)opencloud(dot)com>
To: Guillaume Cottenceau <gc(at)mnc(dot)ch>
Cc: pgsql-jdbc(at)postgresql(dot)org
Subject: Re: performance issue
Date: 2008-03-27 10:23:40
Message-ID: 47EB75AC.9010902@opencloud.com (view raw or flat)
Thread:
Lists: pgsql-jdbc
Guillaume Cottenceau wrote:
> Kris Jurka <books 'at' ejurka.com> writes:
> 
>> When using a PreparedStatement the server must come up with a plan
>> that works for all parameter values.  Since the parameter is unknown,
>> the generated plan doesn't use an index.  Your options are to
>> interpolate the parameter yourself or connect using the
>> protocolVersion=2 URL option which will make the driver do the
>> interpolation prior to passing the query on to the server.
> 
> Kris, actually, is this behaviour considered a bug or a feature?

It was discussed at some length recently, check the list archives. IIRC 
the consensus was to fix the server - essentially, add a mode where the 
driver can tell the server "please replan this statement every time you 
get new parameters", which would allow all the normal planner 
optimizations (constant folding, etc) to be made since it does not need 
to produce a general-purpose plan for all possible parameter values.

-O

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