ST_UnknownSRID()

[dustymugs]

I'd like to see PostGIS provide a SQL function that output's the software's UNKNOWN_SRID. This would help at the present time where it looks like there still is discussion about 0 vs -1.

Also, nothing is stopping a user from changing UNKNOWN_SRID to something other than 0 or -1, say -9999. So a function ST_UnknownSRID would allow users of that PostGIS instance to know what that instance's unknown SRID is.

Heck, I'll write the patch and attach it if everyone is fine with it.

[strk]

The function implementation would be $$ SELECT ST_Srid('POINT(0 0)') $$

I'm not sure what you mean by "nothing is stopping a user from changing UNKNOWN_SRID".

[dustymugs]

Thanks strk! That's easy enough.

As for changing UNKNOWN_SRID, I meant SRID_UNKNOWN. A user could change the value of SRID_UNKNOWN in liblwgeom.h before compiling PostGIS.

[strk]

I wasn't necessarely against wrapping my implementation in a function... maybe an SQL one.

[dustymugs]

It'd be great if you could turn your implementation into an SQL function. I'm always hesitant to make changes to the PostGIS side.