Tuesday, January 3, 2017

Non-spatial Tables

About a year ago, my Twitter timeline blew up. It turns out the Esri User Conference was going on and this got a lot of people chatting together. The root of the matter was a perception that Esri was not providing reasonable support for non-spatial data within GeoPackages. This was leading people towards flawed, clumsy workarounds like inventing spatial columns to tack onto attribute tables(!). Uh, folks, this is not what we had in mind...

I am not here to point fingers and the fact is that both sides had a point. A strict read of GeoPackage v1.1 did not allow non-spatial attribute values. However, in practice data providers routinely need to deliver data that does not contain geometry properties. We agreed that it was not reasonable to require any GeoPackage that contained non-spatial tables to be declared and documented as an "Extended GeoPackage". This does not promote interoperability. 

In response, we modified the standard by adding a new Attributes section that describes how to store non-spatial attribute tables in a GeoPackage. The new section is present in the on-line (working) copy of the specification and it will be incorporated in the next release (tentatively numbered GeoPackage 1.2). We hope that this addition will clarify things and encourage people to use GeoPackages as intended. We consider the change to be low-risk because it creates a new encoding option that would be ignored by previous versions of the standard.

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