From: Dave Cramer <pg@fastcrypt.com>
To: gene@sotech.us
Cc: pgsql-jdbc@postgresql.org
Cc: pgsql-performance@postgresql.org
Subject: Re: does prepareThreshold work? forced to use old driver
Date: Mon, 26 Feb 2007 12:28:37 -0500
Message-ID: <61223CAE-09EB-4FC0-987D-1542AA0F03F1@fastcrypt.com> (raw)
In-Reply-To: <430d92a20702260812le88fb59w3ec40089db7b54dd@mail.gmail.com>
References: <430d92a20702260812le88fb59w3ec40089db7b54dd@mail.gmail.com>
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
>
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To: pgsql-performance@postgresql.org
Cc: pg@fastcrypt.com, gene@sotech.us, pgsql-jdbc@postgresql.org
Subject: Re: does prepareThreshold work? forced to use old driver
In-Reply-To: <61223CAE-09EB-4FC0-987D-1542AA0F03F1@fastcrypt.com>
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