definition of natural mapping

<http://www.w3.org/2001/sw/rdb2rdf/r2rml/#natural-mapping> includes an almost exhaustive list of defined SQL datatypes.

Bullet 2 specifies "If dt is a character string type, then the result is a plain literal without language tag whose lexical form is the SQL data value."
  Given that the rest of the datatypes are listed, including INTERVAL which specifically has no defined mapping in DM or R2RML, I propose that bullet 2 list string types: "If dt is a character string type, i.e. CHARACTER, CHARACTER VARYING or CHARACTER LARGE OBJECT, then…"

Bullet 4 says "Otherwise, the result is a plain literal without language tag whose lexical form is the SQL data value cast to string." Given that we've already covered the SQL datatypes, I think this line as the potential to do more harm than good. (E.g. many DBs have native support for XML but we probably don't want to imply that XML is serialized as a (canonicalized?) plain literal. I proposed to strike the line.
An alternative would be to refine http://www.w3.org/2001/sw/rdb2rdf/directMapping/LC/#defn-literal_map to say [[
Definition literal map: a mapping from an SQL value with a datatype to:

 • For row nodes, a canonical RDF literal representation of the column value as defined in points 1-3 in R2RML section 10.2 Natural Mapping of SQL Values.
 • For other R2RML natural RDF literal representation of the column value as defined in points 1-3 in R2RML section 10.2 Natural Mapping of SQL Values.
]] (note the added "points 1-3 in" text).

-- 
-ericP

Received on Wednesday, 11 January 2012 11:29:12 UTC