Ooops.
Thanks for enlightening me this time. Will be more careful on the next :)
> -----Mensaje original-----
> De: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED]]En nombre de David
> Jencks
> Enviado el: lunes, 24 de septiembre de 2001 21:08
> Para: [EMAIL PROTECTED]
> Asunto: Re: [JBoss-dev] EJB/QL - JBoss extentions
>
>
> I always think the best solution is to ask the right question so there are
> <= 7 pieces of info in the answer....;-)
>
> A couple months ago there was an enormous discussion of this in the
> firebird development list -- we ended up impelementing limit and
> skip. The
> solution you propose has a problem if you are ordering on more than one
> column (your example in fact is wrong, order by and where disagree). With
> more than one column in order by, you have to write a horrendous > clause
> nested to the depth = number of columns in order by.
>
> Of course, limit and skip allow you to lose records and see records twice
> if the underlying table changes between calls.
>
> david jencks
>
> On 2001.09.24 15:00:43 -0400 Ignacio Coloma wrote:
> > > Dave Smith wrote:
> > > > Keep the result set open, retieve from the set as
> necessary, probably
> > > > using a cursor. That way if someone is doing a search that has
> > > 1 million
> > > > records and after I display the first 10 and the client chooses the
> > 3rd
> > > > one, we have only created 10 objects.
> > > No, no, no! We can't keep the result set open!
> > > 1) having open result set and open Connection for each client,
> > > we'll end up with too many open connections and too many open result
> > > sets (256 open cursors by default in Oracle).
> > > 2) How about transaction bounds? Can you keep cursor open after
> > > transaction ends? I don't think so.
> >
> > What about making an automatic paging? Think about something
> LIKE an open
> > cursor. I'll try to be brief. Suppose this query to return 1,000,000
> > records:
> >
> > SELECT ID, NAME FROM TABLE
> > ORDER BY NAME;
> >
> > Suppose that you make a PagedCollection (configurable from
> > jbosscmp-jdbc.xml) that only get the first 50 records (and you close the
> > resultset). You show them. When someone tries to get the #51 record and
> > so
> > you make another call (possibly in another new Transaction context)
> >
> > SELECT ID, NAME FROM TABLE
> > WHERE ID > #the ID of record 50#
> > ORDER BY NAME;
> >
> > And so on. It would be more effective than any solution the programmer
> > could
> > make by hand. Are there Transaction consecuences on this? I could be
> > missing
> > something.
> >
> > My 2c.
> >
> >
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> >
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