Re: R2RML - SQL string representations

On Mon, Nov 21, 2011 at 12:03 PM, Richard Cyganiak <richard@cyganiak.de>wrote:

> On 21 Nov 2011, at 17:24, David McNeil wrote:
> > The R2RML spec [1] has language in section 10.3, that prescribes the
> mapping of SQL string values to plain literals. This surprises me, I would
> expect SQL strings to map to XSD strings. My understanding is that the RDF
> group is moving away from plain literals. What do you think of changing
> this to map SQL strings to XSD strings?
>
> The current behaviour should remain IMO. In the wild, plain literals are
> more common than xsd:string typed literals by an order of magnitude or so
> (I have the numbers somewhere). We should optimize for the common case.


I don't find this a compelling argument.


> And it's already easy to generate xsd:strings simply by specifying the
> rr:datatype.
>

I would rather not require the user to add this to define the obvious,
natural mapping of a column.


> In RDF 1.1, there is no difference between plain literals and xsd:string
> typed literals. They are the same thing. So it's not a move away from plain
> literals, it's just abolishing a distinction. If R2RML were to target RDF
> 1.1, then it wouldn't matter if we said “generate a plain literal” or
> “generate an xsd:string typed literal” – it would result in the same graph.
> But as long as we target the old RDF, the distinction matters.
>

My understanding is that it is something more like: the direction is to use
typed literals rather than plain literals. To be in keeping with this
spirit R2RML would produce strings as xsd:string typed literals.

-David