[Qgis-developer] delete selected features slow (because of featurecount/events)??

Richard Duivenvoorde rdmailings at duif.net
Mon Nov 14 07:55:02 PST 2016

Hi Dev's,

having a small dataset of 300 features (from an online service).

I want to quickly remove most/all of those features, request a new set 
an put them in the same vectorlayer (in a python plugin).

All ok, untill you activate the 'show feature count' in the legend.

If you show the featurecount, it looks like the features are deleted one 
by one: you can see the featurecount go down to zero... ( but I also 
have dataset with a lot more features :-( ) and it takes several (ten's) 

Easy testable:

- load some data, tick the 'show feature count' tickbox in the legend.
- make the layer editable and select all features
- make sure the layer is current in the legend

do the following in the python console:


you can see the 'feature count' go down one by one (slowly...)

while... if you do it outside of python, using the little red 
delete-basket in the edit-toolbar. All features are deleted in a blink! 
Also if you show the featurecount...

I tried some different ways, but could not find a quick way?

Do I miss something/a quicker way?

I thought that it maybe had something to do with filling up the 
'editbuffer', so tried with and without the 'edit' construct [0]
But in this case I just do not want an edit-buffer anyway..


Richard Duivenvoorde


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