[Qgis-developer] have aggregate/window expressions ever been discussed?
giohappy at gmail.com
Fri May 23 14:17:32 PDT 2014
it's a long time I think to what you're descriibing, and that would
definitely be on a higher level then aggregate expressions alone. This
level of abstraction would also be basis for a map/reduce pattern analysis.
It would be great to know some more about what has been discussed so far.
Il 23/mag/2014 22:44 "Régis Haubourg" <regis.haubourg at eau-adour-garonne.fr>
> well, this is something I miss, coming from Mapinfo world.
> Some tests are being made currently on French ministry of ecology, and by
> Nathan also, to head to some kind of a layer abstraction, based on ogr
> virtual layer and ogr sqlite engine.
> Once done, that would open a large field of new features and dedicated
> - SQL assistant (mapinfo like / qspatialite like) on any loaded data
> and without any explicit import step. This includes aggregate functions
> - virtual attribute or spatial columns based on functions
> - ETL feature for changing data types and structure
> FME is providing such kind of SQLexecutor, with some limits currently, and
> that is extremly powerfull in processing tools, allowing to take full
> advantage of existing algorithm for geospatial computing, and SQL-spatial
> SQL for attribute queries AND processing.
> If we find a way to be sure that any datasource can be correctly used
> without caveats hard to understand for the end user, I think we will have
> the best GIS tool ever done for non 3D uses. Still I see some limits with
> SQLITE. For instance, many SQL clauses are partially supported. Or
> calculated fields in view can't be explicitly cast, so QGIS should have to
> guess data type based on a data scan (a major unadressed issue of sqlite)
> I wish I had more time now to investigate by myself.
> Nathan , Hugo , could you tell us more on that topic? is ogr sqlite engine
> the right target or does is have to much limitations?
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