[postgis-devel] Motion: vote for considering SRID <= 0 as "unknown"

Paul Ramsey pramsey at opengeo.org
Tue Oct 4 10:18:20 PDT 2011

I love ISO language.

On Tue, Oct 4, 2011 at 10:11 AM, Chris Hodgson <chodgson at refractions.net> wrote:
> Sandro Santilli wrote:
>> On Tue, Oct 04, 2011 at 03:54:28PM +0100, Mark Cave-Ayland wrote:
>>> My only comment would be what do the various standards (SQL-MM/OGC)
>>> say about SRID values? As long as they don't specify anything, I
>>> guess we have a bit more freedom to interpret the specification as
>>> fits best with PostGIS.
>> All I can find about SRID in OGC SFS 1.1:
>>  Before a geometry can be constructed and inserted into a table,
>>  the corresponding row for its SRID must exist in the
>>  SPATIAL_REFERENCE_SYSTEMS table, else construction of the geometry
>>  will fail.
>> There's no mention of the possibility for a geometry to have _no_ srid.
>> The SRID field in spatial_ref_sys and geometry_columns is of type
>> "integer" (but there's no case of "unsigned" in the whole document so
>> that isn't necessarely a sign of the fact that we should support <0).
>> The SQL/MM doesn't seem any different in that reguard. In both there's no
>> concept of "unknown" srid.
> I thought the entire motivation for switching to the unknown=0 semantic was
> for some kind of standards compliance... if this isn't in any standard, why
> are we doing it again? (I'm seriously asking the question - what is the
> positive side of this change?)
> Chris
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