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

[Nyall Dawson]

On 31 Dec 2015 2:01 AM, "Stefan Ziegler" <stefan.ziegler.de at gmail.com>
wrote:
>
> 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?

Try with the current master version - this should be MUCH faster now. I'd
love to hear any feedback of how you find the changes improve (or don't
improve!) your situation.

Nyall

>
> regards
> Stefan
>
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