[Qgis-developer] Filter on joined tables

Vincent Picavet vincent.ml at oslandia.com
Fri Feb 14 02:24:43 PST 2014


Le vendredi 14 février 2014 11:11:42, Martin Dobias a écrit :
> On Fri, Feb 14, 2014 at 4:36 PM, Hugo Mercier <hugo.mercier at oslandia.com> 
> I think there should be a switch in the GUI allowing the user to do
> filtering with native query (if supported by provider) or with
> QgsExpression (always supported, allows joined attributes in join).
> For simple cases the QgsExpression filter could be even translated to
> provider's native subset query for greater efficiency.

On a side note, there seems to be currently a lot of new features coming in 
QGIS which look like database features. Join tables, relations, filtering, 
indexing ... 

We should probably take a moment of reflection sometime to think about it from 
a general point of view. We do not want to reimplement a database inside QGIS, 
as we already have an embedded one (SQLite/Spatialite), but we want to keep as 
general as possible in terms of format combinations and features available in 
Some rules for development architecture on this topic would be great to have, 
to avoid code complexity and (potentially bad) reimplementation of existing 

Not that I have a good solution ready, but just to raise the subject for 
discussion. Do not hesitate to start a new thread if you think it is worth it.


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