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Message-ID: <56a83cd00705140913s1d74e108p804da067c84d8b82@mail.gmail.com>
Date: Mon, 14 May 2007 09:13:28 -0700
From: "David Van Couvering" <david@vancouvering.com>
Sender: david.vancouvering@gmail.com
To: "Derby Discussion" <derby-user@db.apache.org>
Subject: Re: maxrows - what does it really mean?
In-Reply-To: <20070514114406.GE14950@atum01.norway.sun.com>
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References: <56a83cd00705111529p22af61e9l4a7dcff9f55fa5bb@mail.gmail.com>
	 <3B344FED-5C5B-47FB-9E3A-9A248E96B1D1@SUN.com>
	 <20070514114406.GE14950@atum01.norway.sun.com>

OK, so do I have it right that the right way to "hint" to the driver
to not cache all one million rows when I only need ten rows is to use
setMaxRows()?

Is there a SQL standard way to "hint" to the server not to *process*
all one million rows (e.g. in the order by case)?

Thanks,

David

On 5/14/07, Bernt M. Johnsen <Bernt.Johnsen@sun.com> wrote:
> What David wants, is the feature rgistered in
> https://issues.apache.org/jira/browse/DERBY-581
>
> >>>>>>>>>>>> Craig L Russell wrote (2007-05-13 12:06:38):
> > >Also, how is maxrows related to the fetch size of a ResultSet?
> >
> > As I understand it, the fetch size relates to the number of rows
> > returned by the server to the client for each round trip to the
> > database. So theoretically the two numbers are independent. There's
> > no specified interaction except for the obvious one: requesting a
> > fetch size exceeding the maxrows doesn't make sense since there will
> > never be more than maxrows returned, and fetch size would effectively
> > be ignored.
>
> Fetch Size is in the JDBC spec defined to be an *optimization hint*
> from the application to the driver. It has no semantic meaning
> whatsoever, but may e.g. influence the number of rows prefetched per
> roundtrip and thus influence the overall performance of your
> application.
>
>
> --
> Bernt Marius Johnsen, Database Technology Group,
> Staff Engineer, Technical Lead Derby/Java DB
> Sun Microsystems, Trondheim, Norway
>