[QGIS-Developer] QGIS 3 > Processing: some test

Paolo Cavallini cavallini at faunalia.it
Mon Jun 19 02:22:30 PDT 2017

Il 19 giugno 2017 11:19:05 CEST, Giovanni Manghi <giovanni.manghi at gmail.com> ha scritto:
>Hi Nyall,
>>> Our (hopefully friendly!) rivalry on this point continues :) I think
>>> can win you over for 3.0 when we widely rollout the massive benefits
>>> which are possible only in native algs, such as the support for
>>> dynamic parameters. But we'll see....
>> By the way - I'd love to see you re-run your earlier benchtests after
>> of native vs non-native algs after
>> https://github.com/qgis/QGIS/pull/4707 is merged! For me that PR
>> a ridiculously huge improvement in using processing with memory
>> layers.
>I waited a Windows osgeor4w master build that included your new native
>c++ dissolve tool.
>I tested it (on the same platform and conditions) against qgis 2.18.9
>nightly, that also write debug output.
>and dissolving by "distrito" the ogr2ogr based tool is 2/3 seconds
>faster than the new native one.
>which is a clip of a much larger and complex layer, and dissolving by
>"aaaaa" (sorry for the column name), the ogr 2ogr based tool does the
>job in about 20 seconds.
>The new native dissolve tool runs for a split second and outputs a few
>polygons in vastly incomplete result.
>Trying to dissolve all polygons (and operation that the ogr2ogr based
>tool does with no issues) with the native tool it results in a python
>error and and infinite running hourglass.
>An error has occurred while executing Python code:
>SystemError: returned a result with an error set
>Traceback (most recent call last):
>line 84, in raise_error
>    'Features with invalid geometries found. Please fix these
>geometries or specify the "Ignore invalid input features" flag'))
> Message:
>  | Features with invalid geometries found. Please fix these
>geometries or specify the "Ignore invalid input features" flag
> Stack:
>    None
>The above exception was the direct cause of the following exception:
>Traceback (most recent call last):
>line 246, in accept
>    result = executeAlgorithm(self.alg, parameters, context, feedback)
>line 338, in executeAlgorithm
>    result = alg.run(parameters, context, feedback)
>SystemError:  returned a result with an error set
>Interesting the massage
>"Features with invalid geometries found. Please fix these geometries
>or specify the "Ignore invalid input features" flag"
>because the option is not available in the tool. I still strongly
>argue that anyway -if it is really a problem of bad geometries- we
>miss a clear suggestion and workflow to allow the user solve this
>situation. In my point of view the option in such tools should not be
>"skip the invalid geometries" but to *fix* them.
>-- G --
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Thanks Giovanni, very interesting.
All the best.
Sent from mobile. Sorry for being short
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