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Re: does prepareThreshold work? forced to use old driver

From: Gene <genekhart(at)gmail(dot)com>
To: "Dave Cramer" <pg(at)fastcrypt(dot)com>
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 17:41:24
Message-ID: 430d92a20702260941j58dd77adsb9b48ed6511230ec@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-jdbcpgsql-performance
Thank you! setting the protocolVersion=2 works with the newer driver.
I'm still puzzled as to why the prepareThreshold=0 doesn't force the
replan though.

On 2/26/07, Dave Cramer <pg(at)fastcrypt(dot)com> wrote:
>
> 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.
>
> Dave
> > --
> > thanks, G
> >
> > ---------------------------(end of
> > broadcast)---------------------------
> > TIP 3: Have you checked our extensive FAQ?
> >
> >               http://www.postgresql.org/docs/faq
> >
>
>


-- 
Gene Hart
cell: 443-604-2679

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