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Re: does prepareThreshold work? forced to use old driver

From: Dave Cramer <pg(at)fastcrypt(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 17:28:37
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-jdbcpgsql-performance
On 26-Feb-07, at 11:12 AM, Gene wrote:

> hi!
> 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 :)
> Could someone point me to a jdbc src file where I could just disable
> server-side prepared statements entirely?
you can just add protocolVersion=2 to the url and it will not use  
prepared statements.

setting prepareThreshold=0 just tells it not to use named statements.  
It will still use statements but won't cache them.

Are you sure the problem is with cached statements ? There are issues  
where prepared statements won't use the index if you don't use the  
correct type.

> -- 
> thanks, G
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