[Qgis-developer] Spatial index - what about having it automatically created and updated ?

Martin Dobias wonder.sk at gmail.com
Thu Feb 27 02:08:02 PST 2014


On Thu, Feb 27, 2014 at 4:47 PM, kimaidou <kimaidou at gmail.com> wrote:
> Hi list,
> I have some concerns about spatial indexes in QGIS. Spatial indexes are very
> usefull, and for me rather mandatory as soon as you deal with more than 100
> features.
> I would like to share some ideas about them :
> 1) Extend QGIS so that it can create spatial indexes for more vector format.
> If I am correct, for now only Shapefiles and Database vector layers can have
> a spatial index created by QGIS . Why not for GeoJson, CSV files, etc ?

The create spatial index functionality is handled by data provider -
in this case GDAL/OGR - at some point it was available only for
shapefiles, not sure if anything changed since then.

> 2) If possible, create a spatial index for each vector layer added to the
> canvas if no one is already present. Since it is a quite fast operation, the
> small time needed is worth it.

I am not sure this is the right thing to do it automatically. It could
however suggest it for large layers for better performance.

> 3) If possible, update the spatial index (replace the old qix by a new one)
> every time the vector layer is updated. No need to do so for database
> layers, but this can be very usefull for big shapefiles. I have seen some
> people creating a spatial index, then as time passes, they add more and more
> data into the shapefile but forget to update the spatial index. Sometimes
> this can lead to some data not displayed in QGIS because QGIs seems to rely
> on the outdatedSpatial index.

Doesn't OGR handle the update of the spatial index automatically?


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