[postgis-devel] ST_MakeValid() behaviour

[Sandro Santilli]

On Sat, Apr 17, 2021 at 10:12:14AM -0700, Paul Ramsey wrote:
> Coming soon to GEOS 3.10 is a new implementation of a "validity repairer", currently named GeometryFixer.
> 
> https://github.com/libgeos/geos/pull/433
> 
> Open question is whether to bind the GEOS default GEOSMakeValid() CAPI to it. It provides (we think, arguably) more "expected" outputs for various invalid cases, and is almost certainly faster than the existing implementation. On the other hand, it's *different*, so people would get different results from ST_MakeValid() depending on the GEOS version under their PostGIS.
> 
> We could still leave the old algorithm *accessible*, via extra parameters and knobs and switches, as Dan notes in a comment on the PR. Question is, can we switch out the default behaviour, or are we going to end up with ST_MakeValid() and ST_GeometryFix() (or something).

How about implementing options ?
Ideally the options would express the difference in behavior, so that
the user specifies which behavior she wants. Can such differences be
expressed in a clear way ?

--strk;