[gdal-dev] Rasterlite driver does not create layer statistics

Even Rouault even.rouault at mines-paris.org
Sun Sep 16 05:56:06 PDT 2012


Le vendredi 07 septembre 2012 14:51:24, Jukka Rahkonen a écrit :
> Hi,
> 
> Even wrote a few weeks ago:
> 
> " I've just pushed an improvement (r24800) in which the SQLite driver can
> use those cached values, if they are up-to-date. The up-to-dateness is
> determined by checking that the timestamp of the last
> 'UpdateLayerStatistics' event recorded in the 'spatialite_history' table
> matches the timestamp of the file. When creating a new Spatialite DB or
> updating it with the OGR API, the SQLite driver makes sure that the
> statistics are kept up-to-date automatically. "
> 
> Could it be so that even the GDAL Rasterlite driver can utilize layer
> statistics if they exist, it does not create them? I just used a two days
> old GDAL-dev version and I had to run SELECT UpdateLayerStatistics()
> manually for creating the layer_statistics table.

Strange. I just re-tested it (running gdal_translate and gdaladdo) and the 
layer_statistics table is well created and populated.

Perhaps you should re-run it with --debug on to see if something interesting 
shows up.

> 
> It would be good to mention statistics and how they can be creted/refreshed
> in the performance hints of OGR/SQLite and GDAL/Rasterlite drivers.
> Especially with Rasterlite it is not at all obvious to do
> ogrinfo the.db -sql "SELECT UpdateLayerStatistics()"

Would you be interested in contributing a documentation patch for that ?

> 
> -Jukka Rahkonen-
> 
> 
> 
> 
> 
> 
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