[postgis-devel] Validity flag

[Hugo Mercier]

On 29/02/2016 17:50, Paul Ramsey wrote:
> Yes, it's our most complete, but it's not fully complete I think,
> since the 3d stuff wasn't documented in it, though they just follow
> the pattern of polygons, I believe.
> 
> WE CANNOT JUST TACK IN ANOTHER BYTE.
> 
> Remember that. The whole header is carefully set up to ensure that all
> the ordinates are on 8-byte alignment, so adding in an other single
> header byte destroys that, and all the direct coordinate access that
> has been added to the system since then. Any attempt to add more flags
> will have to go with a comprehensive reorganization of the
> serialization to try and maintain compactness and also maintain
> alignment.

What about putting an extra byte at the *end* of the data ?
I know it is hacky, but ... can't find better yet.
It could invalidate memory cache for huge geometries, but should not
disturb existing code