Opened 3 years ago

Last modified 2 months ago

#4934 new task

Deprecate topology function creating invalid topologies — at Version 2

Reported by: strk Owned by: strk
Priority: medium Milestone: PostGIS 3.5.0
Component: topology Version: 2.5.x -- EOL
Keywords: Cc:

Description (last modified by strk)

Some topology functions are creating invalid topologies, and are documented to do so. They were written before SQL/MM full specification was implemented, so it wasn't that easy to create valid topologies.

Nowadays those functions just make it harder to maintain the codebase as there are testcases proving the functionality of some of them still works in presence of invalid topologies and we impelment code to ensure invalid topologies are still somehow handled. Better stop now :)

Such functions are (list to be grown I guess):

  • AddEdge (does not do edge linking nor face labeling)
  • AddNode (allows inserting isolated nodes with wrong containing_face)
  • AddFace (allows leaving unresolved dangling edges)

Another idea would be to *allow* creating invalid topology but somehow encode the kind of invalidity when doing so. For example in the AddLineStringNoFace function used as part of the proposed https://git.osgeo.org/gitea/postgis/postgis/pulls/28 change we encode the concept of "unknown side faces" by using the -1 pivot value in the left_face and right_face of edges with such unknown faces.

Change History (2)

comment:1 by strk, 3 years ago

Description: modified (diff)

comment:2 by strk, 3 years ago

Description: modified (diff)
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