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From "Peter Ondruška" <peter.ondru...@gmail.com>
Subject Re: getting first k rows from a query that satisfy some additional condition
Date Mon, 27 Oct 2008 22:35:09 GMT
Post the query and table and index DDL.

On Mon, Oct 27, 2008 at 23:10, Amir Michail <amichail@gmail.com> wrote:

> On Mon, Oct 27, 2008 at 6:07 PM, Peter Ondruška
> <peter.ondruska@gmail.com> wrote:
> > Well, in that case database engine has to read all relevant rows, then
> sort
> > and only after that it can display the first row(s).
>
> Why doesn't it use the index on the column specified in order by?
>
> Amir
>
> >
> > On Mon, Oct 27, 2008 at 23:02, Amir Michail <amichail@gmail.com> wrote:
> >>
> >> On Mon, Oct 27, 2008 at 5:59 PM, Peter Ondruška
> >> <peter.ondruska@gmail.com> wrote:
> >> > Please, post the query you are running.
> >> > There are queries where setMaxRows will not be faster, for example if
> >> > you do
> >> > GROUP BY or ORDER BY.
> >>
> >> The order is important, so I'm using order by.
> >>
> >> Amir
> >>
> >> >
> >> > On Mon, Oct 27, 2008 at 22:51, Amir Michail <amichail@gmail.com>
> wrote:
> >> >>
> >> >> On Mon, Oct 27, 2008 at 5:45 PM, Daniel Noll <daniel@nuix.com>
> wrote:
> >> >> > Amir Michail wrote:
> >> >> >>
> >> >> >> Hi,
> >> >> >>
> >> >> >> What is a good way for efficiently getting the first k rows
from a
> >> >> >> query that also satisfy some additional condition to be determined
> >> >> >> using Java code?
> >> >> >
> >> >> > setMaxRows(int) is the standard way of doing this in JDBC, it
only
> >> >> > falls
> >> >> > over if you later want to retrieve rows k..(2k-1).
> >> >> >
> >> >> > Daniel
> >> >> >
> >> >>
> >> >> It's slow with setMaxRows.
> >> >>
> >> >> Amir
> >> >>
> >> >> >
> >> >> > --
> >> >> > Daniel Noll                            Forensic and eDiscovery
> >> >> > Software
> >> >> > Senior Developer                              The world's most
> >> >> > advanced
> >> >> > Nuix                                                email data
> >> >> > analysis
> >> >> > http://nuix.com/                                and eDiscovery
> >> >> > software
> >> >> >
> >> >>
> >> >>
> >> >>
> >> >> --
> >> >> http://chatbotgame.com
> >> >> http://numbrosia.com
> >> >> http://twitter.com/amichail
> >> >
> >> >
> >>
> >>
> >>
> >> --
> >> http://chatbotgame.com
> >> http://numbrosia.com
> >> http://twitter.com/amichail
> >
> >
>
>
>
> --
> http://chatbotgame.com
> http://numbrosia.com
> http://twitter.com/amichail
>

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