Re: [gnome-db] libgda cursor support

["Vivien Malerba" <vmalerba gmail com>]

On 9/27/07, Murray Cumming <murrayc murrayc com> wrote:
>
> On Thu, 2007-09-27 at 14:39 +0200, Vivien Malerba wrote:
> > > > meaning it could not set the iter at the requested row, which is why
> > > > it always returns the same value. The reason it returns FALSE is that
> > > > it's not implemented (specifically the i_iter_at_row virtual method is
> > > > not implemented). Of course it an iterator can move forward and
> > > > backward, there could be a default implementation to move it to a
> > > > desired row...
> > >
> > > I guess this should be implemented with FETCH ABSOLUTE.
> > > http://www.postgresql.org/docs/8.2/static/sql-fetch.html
> > > Does that seem appropriate?
> >
> > This could be implemented like that in the GdaPostgresCursorRecordset, yes.
> >
> > Otherwise for a more general approach (that is in
> > gda_data_model_move_iter_at_row() which is called if no specific
> > implementation exists)  we just need to call
> > gda_data_model_iter_move_{prev,next} as many times as requested (and
> > in the case of the postgres cursor recordset there might even be no
> > performance penalty at all because it fetches chunks of rows ar once).
>
> But wouldn't that mean that we have to fetch the data for 1000 rows (100
> chunks of 10, for instance) if I just want the data for row 1 and row
> 1000?

You're right, I had not thought abou that... Then the only way is to
use FETCH ABSOLUTE into the GdaPostgresCursorRecordset code.

Vivien