[Qgis-developer] have aggregate/window expressions ever been discussed?
regis.haubourg at eau-adour-garonne.fr
Fri May 23 13:44:13 PDT 2014
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 source
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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