Bug report #11186

Deleting records from a table is very slow when the table is open for viewing

Added by Paolo Cavallini about 8 years ago. Updated over 3 years ago.

Category:Attribute table
Affected QGIS version:2.18.17 Regression?:No
Operating System: Easy fix?:No
Pull Request or Patch supplied:No Resolution:end of life
Crashes QGIS or corrupts data:No Copied to github as #:19498


Tens of minutes for a PostGIS table with 200k records, with qgis taking 100% of CPU. The issue was apparently fixed some time ago by Kuhn by introducing some kind of "batch job detection" on attribute table side.


#1 Updated by Matthias Kuhn about 8 years ago

The problem most likely is introduced by the fact, that each feature is deleted with a separate call to QgsVectorLayer::deleteFeature( QgsFeatureId fid ) which in turn leads to one signal being emitted for each deleted feature and the attribute table updates accordingly with a expensive operation.

The same applies to adding features/changing attributes.

IIRC I resolved it for changing attributes by watching for editCommandStarted()/editCommandEnded() signals on attribute table side and buffering any edit happening in between, but only updating the attribute table once in the end (batch job detection).

The same could be done for deleting features on attribute table side. Instead I would propose to implement this feature directly inside QgsVectorLayer and emit batched signals for operation happening inside an edit command and per-operation signals when outside an edit command. This would have the advantage of not having to reinvent the wheel for every part where expensive operations can be performed once per edit command.

#2 Updated by Giovanni Manghi over 5 years ago

  • Easy fix? set to No
  • Regression? set to No

#3 Updated by Paolo Cavallini over 4 years ago

  • Status changed from Open to Feedback
  • Description updated (diff)

Matthias, do you consider this fixed?

#4 Updated by Giovanni Manghi over 4 years ago

  • Affected QGIS version changed from 2.4.0 to 2.18.17
  • Status changed from Feedback to Open

Such operation on large tables is still painfully slow on 2.18. Not sure about 3.

#5 Updated by Giovanni Manghi over 3 years ago

  • Resolution set to end of life
  • Status changed from Open to Closed

End of life notice: QGIS 2.18 LTR


QGIS 3.4 has recently become our new Long Term Release (LTR) version. This is a major step in our history – a long term release version based on the massive updates, library upgrades and improvements that we carried out in the course of the 2.x to 3x upgrade cycle.

We strongly encourage all users who are currently using QGIS 2.18 LTR as their preferred QGIS release to migrate to QGIS 3.4. This new LTR version will receive regular bugfixes for at least one year. It also includes hundreds of new functions, usability improvements, bugfixes, and other goodies. See the relevant changelogs for a good sampling of all the new features that have gone into version 3.4

Most plugins have been either migrated or incorporated into the core QGIS code base.

We strongly discourage the continued use of QGIS 2.18 LTR as it is now officially unsupported, which means we’ll not provide any bug fix releases for it.

You should also note that we intend to close all bug tickets referring to the now obsolete LTR version. Original reporters will receive a notification of the ticket closure and are encouraged to check whether the issue persists in the new LTR, in which case they should reopen the ticket.

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#6 Updated by Paolo Cavallini over 3 years ago

It seems to go well on 3.6.

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