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Re: SOLVED ... Re: Getting rid of a cursor from JDBC .... Re: [PERFORM] Re: HELP: How to tame the 8.3.x JDBC driver with a biq guery result set

From: Nikolas Everett <nik9000(at)gmail(dot)com>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Kris Jurka <books(at)ejurka(dot)com>, Dave Crooke <dcrooke(at)gmail(dot)com>, Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov>, pgsql-jdbc(at)postgresql(dot)org, pgsql-performance <pgsql-performance(at)postgresql(dot)org>, Scott Carey <scott(at)richrelevance(dot)com>
Subject: Re: SOLVED ... Re: Getting rid of a cursor from JDBC .... Re: [PERFORM] Re: HELP: How to tame the 8.3.x JDBC driver with a biq guery result set
Date: 2010-04-21 15:07:11
Message-ID: q2qd4e11e981004210807ua364abbbua4ae2fb0a91ac053@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-jdbcpgsql-performance
On Wed, Apr 21, 2010 at 10:41 AM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:

> On Tue, Apr 20, 2010 at 5:05 PM, Kris Jurka <books(at)ejurka(dot)com> wrote:
> > The reason this is not done is that the mechanism used for fetching a
> piece
> > of the results at a time can change the query plan used if using a
> > PreparedStatement.  There are three ways to plan a PreparedStatement:
> >
> > a) Using the exact parameter values by substituting them directly into
> the
> > query.  This isn't really "planned" as you can't re-use it at all.  This
> is
> > only available using the V2 protocol.
> >
> > b) Using the parameter values for statistics, but not making any stronger
> > guarantees about them.  So the parameters will be used for evaluating the
> > selectivity, but not to perform other optimizations like
> contraint_exclusion
> > or transforming a LIKE operation to a range query. This is the default
> plan
> > type the JDBC driver uses.
>
> Hmm.  I didn't think this was possible.  How are you doing this?


More to the point is there some option that can shift you into method a?
 I'm thinking of warehousing type applications where you want to re-plan a
good portion of your queries.

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