[Qgis-developer] Performance of QGIS expressions "attribute" and "get_feature"

Stefan Ziegler stefan.ziegler.de at gmail.com
Wed Dec 30 07:01:42 PST 2015


Hi

I add a virtual field to a layer with e.g. following expression

attribute(get_feature('pnf_pnf','t_id',afrom),'year')

This works really great. Then I'm using this new virtual field for
filtering the features in the rule based renderer. How does affect this the
rendering performance? It seems that it really slows down rendering even
with layers with only approx 600 features each.

If so, can the speed improved with e.g. some to develop caching mechanism?

regards
Stefan
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