Bug report #7616
Select is slower if canvas show a lot of features
|Affected QGIS version:||master||Regression?:||No|
|Operating System:||Easy fix?:||No|
|Pull Request or Patch supplied:||No||Resolution:|
|Crashes QGIS or corrupts data:||No||Copied to github as #:||16542|
The selection of features from the attribute table becomes very slow if the full extent of a layer is visible on the canvas.
For example, applying a filter to a polygon shapefile and selecting ~900 features, with the full extent of the layer visible on canvas, takes 21s. If the layer is at a scale of about 1:2.000, the same selection is almost instantaneous.
This happens both in master and 1.8.
Something similar happens at the start/stop editing (toggle editing).
This is most noticeable with heavy and more complex layers.
#2 Updated by Pedro Venâncio over 8 years ago
The performance increased dramatically after your commit! Thank you very much for your work!
The only situation where I did not noticed a performance boost, was in this particular situation.
As I said, this is not a regression, since it also occurs in QGIS 1.8.
#3 Updated by Matthias Kuhn over 8 years ago
I will need some more information to investigate this.
- Does it only happen with the attribute table open?
- How long does rendering take without the attribute table open?
- How are you selecting features (on the attribute table, on the canvas, with an expression...)
- Do you have a filter applied in the attribute table window?
- How many features are there in total?
I'm sorry, but I can't promise a fix. It took me already some time to get the current improvements.
#4 Updated by Pedro Venâncio over 8 years ago
Sorry, but after some more tests, I see that this problem, at this time, only occurs when the layer is being edited (toggle editing on).
Moreover, it takes exactly the same time (20 seconds):
- from the moment when I click on toggle editing button until the moment the editing is ready;
- as the time it takes to select one single polygon from the attribute table (regardless of the size/area of that polygon);
- as also the time it takes to select one single polygon through canvas with "Select single feature" button.
The time mentioned relate to a polygon layer, with 8612 features.
At this point, I have great difficulty to believe that this problem is related to the attribute table. What do you think?
#6 Updated by Pedro Venâncio over 8 years ago
- Status changed from Feedback to Closed
Matthias you're right, I found a significant increase in performance just disabling the option "Make lines appear less jagged at the expense of some drawing performance" on Rendering settings.
I think we can close this ticket, since it has nothing to do with what initially suspected. And it seems that is directly related to Feature #3200 .