[postgis-devel] Autofix and retry for GEOS overlay ops

[Brian M Hamlin]

PSC, devs, all -
 
  Please consider adding a 'valid' flag to GEOMETRY at the deepest 
levels, as we see in SFCGAL now, for PostGIS 3.x. 
The operations where a 'valid'  state could change, are deterministic 
throughout the system I suspect, and therefore manageable. 
Really, valid is for POLYGON/MULTIPOLYGON but it makes little sense to 
isolate the geometry type. Why not just make it fundemental. 
 
Per a previous conversation, there may be more than one flag, so a 
short word of flag bits is a similar suggestion. 

The discussion of 'modes' would change quite a bit, if this construct 
was pervasive and reliable. 
 
  --Brian

On Sat, 10 Feb 2018 09:21:45 0000, Darafei "Komяpa" Praliaskouski 
<me at komzpa.net> wrote:
.. 
So if we'd like to really do something about invalidity, a "strict 
mode" can help - check validity on output of any geometry-returning 
function, including input parsers. Such a change would make people who 
want to be sure they get an exception in case something is doubtful 
happy. It will also break some clever hacks like 
ST_Buffer(ST_Collect(),0) and make sure you will be debugging GEOS 
every day for at least a year. :)
..