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A way to generate PK-strings or new blank nodes

From: Fabian Pijcke <fabian.pijcke@gmail.com>
Date: Thu, 20 Oct 2011 18:36:01 +0200
Message-ID: <CALebJyECV+76Ci0_hL+1vHgfMNSTSo_Ns2g0Jv+i0WO3cF=_eA@mail.gmail.com>
To: public-rdb2rdf-comments@w3.org
Hi there,

I am currently playing with R2RML, and experiences a few
difficulties while trying to implement a "Direct mapping"
generator as a R2RML graph. (using this mapping on an
INFORMATION_SCHEMA schema should generate the direct

The main problem is to generate the row nodes. I don't
specially want to follow the PK-string defined into the
direct mapping document (it would be nice to do it, but I
don't think it is actually possible without using an SGBDR
specific construction). So I decided to simply use unique
IRIs or unique blank nodes, but this is no more
possible: because I don't know the fields into my tables,
I cannot create a template that will make only unique
values, and I cannot do it for blank node labels anymore.

A solution would be to have a construction such as:

rr:subjectMap [
  rr:termType rr:BlankNode;

(note the absence of rr:constant, rr:column and
rr:template properties)

The behavior would the be, for example, to generate a new
blank node with a reserved name such as "rrauto_X" where X
is a natural ...

Or perhaps does anybody know a way to generate the
PK-string using an R2RML mapping ? Please let me know ...

Best regards,

Fabian Pijcke
Received on Thursday, 20 October 2011 16:36:40 UTC

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