[postgis-devel] ST_MakeValid() behaviour

Sandro Santilli strk at kbt.io
Sun Apr 18 12:14:49 PDT 2021

On Sun, Apr 18, 2021 at 11:17:30AM -0700, Paul Ramsey wrote:

> I think it's fair to say that "MakeValidWIthOptions()" will be added to the design, include options to toggle the overall algorithm, however, that leaves the important question of what to bind generic MakeValid() to, both in GEOS CAPI and in PostGIS ST_MakeValid(). The reality is that users will 99.9% of the time just call ST_MakeValid() and the optionality won't get used. What should that case do?

I think backward compatibility should be preserved,
thus the default would be the old behavior of retaining
all vertices.

NOTE: I remember many cases of Shapefiles where the winding
      order of holes or exterior rings was wrong, resulting 
      in validities like "hole outside shell". This is to say
      that "retain meaning of exterior/interior" is not necessarely
      "better" than "retain all vertices".


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