[postgis-devel] Validity flag

Oliver Courtin olivier.courtin at oslandia.com
Mon Feb 29 03:45:38 PST 2016

Hi Sandro,

>> I like the approach of the validity flag, as long as we have
>> space for it. The ST_MakeValid could probably also set it,
>> for example.
> I've been also thinking that a single bit would not be enough
> to store the validity as the expensive operation we're trying
> to avoid is _checking_ for validity, so we want to encode
> whether or not the geometry was _checked_ in addition to 
> whether it was found _valid_ or _invalid_, so we'd need
> 2 bits.

Why do you think there is a need for a flag handling _invalid_ ?

With only the _valid_ one , if we are sure that geometry is valid, 
we could skip the check validity in SFCGAL (or other backend),
and if we not sure (i.e unknown or not valid), 
we have to do the check validity backend side.

You have something more in mind ?



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