Datatype handling added to R2RML spec (ISSUE-29, ISSUE-48, ISSUE-51)

There's a new section in R2RML that discusses the handling of datatypes:

The definitions and tables in that section are referenced from various places throughout the spec, in particular:

Some noteworthy features:

- it is now an error to have a logical column that cannot be CAST to string
- unknown/user-defined types are CAST to string and mapped to plain literal
- rr:datatype is implicit if unspecified, that is, date column will be xsd:date even without explicit rr:datatype
- explicit rr:datatype that doesn't match the implicit type results in typed literal where the lexical form is simply the result of CAST to string
- implementations MUST support literal well-formedness checks for the 8 supported XSD types
- implementations MAY support literal well-formedness checks for additional types
- ill-typed literal is a data error
- I ignored INTERVAL because it's so freaking complicated
- binary types get mapped to xsd:base64Binary

Please review and comment!

Process: I've set ISSUE-29, ISSUE-48 and ISSUE-51 to Pending Review and propose:

PROPOSAL: Close ISSUE-29; all places that interpret SQL values as string now use "conversion to string"

PROPOSAL: Close ISSUE-48 as it is addressed in

PROPOSAL: Close ISSUE-51; the spec now demands that “supported RDF types” MUST raise data error, and other types MAY raise data error

Received on Thursday, 25 August 2011 23:56:58 UTC