[Qgis-developer] python/ogr problems reading large gml file

[Even Rouault]

Le lundi 02 mai 2016 15:38:45, Richard Duivenvoorde a écrit :
> Hi Devs,
> 
> (below all via python/plugin on Debian/Linux):
> 
> Via a WFS I retrieve 10000 features as GML as data.gml
> To be able to read (attr+geometry) the GML I copy a data.gfs next to it.
> 
> Now all seems ok, untill the number of features returned is > 1500.
> Strange errors like:
> 
> ogrinfo -ro data.gml reports a (None) geometry
> BUT if I 'touch' the data.gfs ogrinfo, then suddenly all is ok
> Seems like ogrinfo does not like the copied gfs at first?
> Permissions are ok. A 'touch /tmp/foo/data.gfs' is enough.

The OGR GML driver only uses the .gfs file if its modification time is equal or 
greater than the the one of the .gml file (to avoid using an outdated .gfs 
file). If you run ogrinfo with --debug on, you'll see a message about that. 
Should probably be a more verbose warning.

> 
> Off course the same holds for QGIS, if I open the retrieved and saved
> gml file as a gml-vectorlayer, a 1000 feature containing one is probably
> ok, but <1500 often fails and the 10000 one ALWAYS fails (untill I
> 'touch' the gfs file).
> IF something goes wrong: there is no exception, and 'layer.isValid()'
> returns true, but geometry/attributes are None at such moment.
> 
> I'm pretty carefull with closing/opening the files (I think), but it
> smells like either files that are still open, OR python loosing it's
> handles or so?
> 
> Anybody some idea on what I am doing wrong?
> Sorry, cannot sent you a wfs-url it's an internal service here.
> 
> Thansk for any pointers
> 
> Regards,
> 
> Richard Duivenvoorde
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