Bug report #13983

Split parts on MultiLineString: discards data

Added by Mike Taves almost 8 years ago. Updated over 4 years ago.

Affected QGIS version:2.12.0 Regression?:No
Operating System:Windows 7 x64 Easy fix?:No
Pull Request or Patch supplied:No Resolution:end of life
Crashes QGIS or corrupts data:No Copied to github as #:21997


The issue is that geometry data is silently discarded when using the Split Parts tool on MultiLineString geometries with QGIS 2.12.1-Lyon (16760fd).

Consider a simple MultiLineString in a PostGIS database: MULTILINESTRING((0 0, 10 0))

Editing the geometry with the Split Parts tool (in the Advanced Digitizing toolbar), e.g., to split the line in the middle will do this: keep only the MultiLineString from the start to the split location, and discard the MultiLineString from the split location to the end, such as MULTILINESTRING((0 0, 5 0)).

An expected result would be something like MULTILINESTRING((0 0, 5 0), (5 0, 10 0)).

A second experiment with MULTILINESTRING((0 0, 5 0), (5 0, 10 0)) will show data loss of other parts that were not split. Splitting the first part will keep the line from the start to the split location, and will discard both the remaining portion of the first part, and all of the second part, so result is MULTILINESTRING((0 0, 2.5 0)). Furthermore, splitting the second part will discard all of the first part, and keep only the start of the second part to the split location, so result is MULTILINESTRING((5 0, 7.5 0)).

An expected result would keep the other parts of the geometry, as well as the new parts that were split, so either MULTILINESTRING((0 0, 2.5 0), (2.5 0, 5 0), (5 0, 10 0)) or MULTILINESTRING((0 0, 5 0), (5 0, 7.5 0), (7.5 0, 10 0)).


#1 Updated by Giovanni Manghi over 6 years ago

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

#2 Updated by Giovanni Manghi over 4 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

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