[Qgis-developer] how to avoid full-table scans to determine primary key, extents?

Nicolas Boisteault boisteault at observatoire-environnement.org
Mon Nov 14 23:48:32 PST 2016



I think your question is related to this issue [1]. 

It is about QGIS Server but the issue is the same. 

QGIS needs a way to declare the extent of a layer to avoid a query that
gets (st_extent) or guesses (st_estimated_extent) the extent. 

[1] : http://hub.qgis.org/issues/14364 

Le 2016-11-15 08:11, Sandro Santilli a écrit : 

> On Mon, Nov 14, 2016 at 04:43:31PM -0800, Chris Nicholas wrote:
>> I have noticed for a long time, that despite checking the "use
>> estimated metadata" box when adding PostGIS layers, QGIS seems to
>> issue 2 full-table scan queries.
> Could you check if an issue mentioning this problem exists already
> on hub.qgis.org and add one if not already present ?
> I've had the same impression and it is possible this was a regression.
> It'd be great to have an automated test guarding against full table
> scans with PostGIS, to secure the feature once for all..
> --strk;
> () Free GIS & Flash consultant/developer
> /\ https://strk.kbt.io/services.html [1]
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[1] https://strk.kbt.io/services.html
[2] http://lists.osgeo.org/mailman/listinfo/qgis-developer
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