[Qgis-developer] [Qgis-user] QGIS loaded millions of entries

[Nathan Woodrow]

Hmm are you sure we don't do this already?

I suspect we do. Each provider can handle the sorting, giving to it by
QgsFeatureRequest, and hand the results back to the caller.  I thought the
attribute table was already implemented this way.

Regards,
Nathan

On Sat, Mar 4, 2017 at 6:03 PM, Tobias Wendorff <
tobias.wendorff at tu-dortmund.de> wrote:

> Am Sa, 4.03.2017, 08:34 schrieb Alessandro Pasotti:
> >
> > Yes, that would be a strategy, but you might run into problem with
> > sorting and filtering if the data provider does not support for it.
>
> All database-like formats, even Shapefile's DBF, support sorting
> on database level. I've never understood, why some applications
> download the whole content first and
>
> Microsoft Access is such a "problem". Some days ago, it has downloaded
> 700 MB of data from the database to figure out "first" and "min/max".
> Access has a "pass-through" function for this to make it directly
> work on database level, but it's somehow hard to handle.
>
> But you're right. For things like sorting in calculation, there
> has to be a different solution, like threaded or staged or using
> "processing" toolbar only.
>
> My system can't even handle to download 3 * 10^6 attributes :(
>
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