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Re: does prepareThreshold work? forced to use old driver

From: Kris Jurka <books(at)ejurka(dot)com>
To: gene(at)sotech(dot)us
Cc: pgsql-jdbc(at)postgresql(dot)org, pgsql-performance(at)postgresql(dot)org
Subject: Re: does prepareThreshold work? forced to use old driver
Date: 2007-02-26 16:45:24
Message-ID: Pine.BSO.4.64.0702261129290.6591@leary.csoft.net (view raw or flat)
Thread:
Lists: pgsql-jdbcpgsql-performance

On Mon, 26 Feb 2007, Gene wrote:

> I've been having some serious performance issues with
> postgresql8.2/hibernate/jdbc due to postgres reusing bad cached query
> plans. It doesn't look at the parameter values and therefore does not
> use any partial indexes.
>
> After trying to set prepareThreshold=0 in the connection string which
> didnt work, even modifying the jdbc driver and forcing it to 0 and not
> working I realized that it must be being ignored. After giving up
> pretty much I tried a much older driver which doesn't use server
> prepared statements at all the problem has gone away and it is once
> again using the partial indexes. How can I get this to work properly
> on the new jdbc driver? I don't really like having to use a 2 year old
> driver to get good performance as you can imagine :)

Something must be going wrong in the setting to zero or your code may be 
setting it to non-zero at some later point.  I believe prepareThreshold=0 
should work.  Do you have a test case showing it doesn't?

Kris Jurka


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