2014-02-27 11:08 GMT+01:00 Martin Dobias <[email protected]>: > Hi > > On Thu, Feb 27, 2014 at 4:47 PM, kimaidou <[email protected]> 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. >
Ah, ok, so I should better ask in GDAL lists ! > > > > 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. > It could be an option, but I did not think it is worth it as the spatial index is fast to create. I agree we could detect if the layer is large and do it only in this case. > > > > 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? > I do not know, I should do some more research... This would be great indeed. > > Regards > Martin >
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