Dealing with topology data corruption on upgrade to 3.6.0

[Regina Obe]

> The 3.6.0 release introduced a bug that results in data corruption:
> https://trac.osgeo.org/postgis/ticket/5983
> 
> This means that whoever upgraded to 3.6.0 while having topology data is now
> in a data-corruption state and any update to their data will make the situation
> worse beacuse they would end up with a mix of valid and invalid rows.
> 
> It would be nice if the proponent of the change which introduced the problem
> (in Cc) would partecipate in the effort of providing a fix for it, and I hope we
> won't repeat the mistake of accepting contributions before all issues raised
> during review are addressed [1]
> 
> [1] https://gitea.osgeo.org/postgis/postgis/pulls/242#issuecomment-13471
> 
> I think this should be announced to the users because as the damage could be
> mitigated by restoring a backup into a 3.5.x version until we find a solution.
> 
> 
> --strk;
> 
>   Libre GIS consultant/developer 🎺
>   https://strk.kbt.io/services.html


We are chatting about this in IRC/matrix.  I'm thinking of a plan that will work as follows to fix.

1) roll back the catalog updates, that should fix existing installs without having to restore from a huge backup
2) Rename the existing domain and topogeometry type - something like  topogeometry_small
3) Create new types (with the existing name, topogeometry, topoelement etc).
4) Put in autocasts to topogeometry_small -> topogeometry 


Unfortunately all this kinda breaks our rule of no new functions or types in a micro, but I don't see how we have much choice here.


Thanks,
Regina