Re: Meeting minutes 2012-05-01

All,

Wrt to the issue "Implementability for tables w/o primary key", I present
the following proposal

PROPOSAL: In the DM spec, replace the following text:

[[
If the table has no primary key, the row node is a fresh blank node that is
unique to this row.
]]

with this:

[[

If the table has no primary key, the row node is a blank node. Distinct
blank nodes MUST be generated for rows with distinct column values. For
duplicate rows with identical values, implementations SHOULD generate a
fresh blank for each duplicate row (resulting in a non-lean RDF graph [RDF
Semantics]). However, if the underlying database system does not provide
any means to reliably differentiate among the rows, then implementations
MAY re-use the same blank node for multiple duplicate rows (resulting in a
lean RDF graph). The lean version does not maintain the relational table's
cardinalities, and hence gives different answers under certain SPARQL
queries. Implementations MUST document and advertise their chosen behavior.
]]


I believe this proposal is a compromise which will allows both types of
implementations.

Juan Sequeda
+1-575-SEQ-UEDA
www.juansequeda.com


On Tue, May 1, 2012 at 12:34 PM, Michael Hausenblas <
michael.hausenblas@deri.org> wrote:

> All,
>
> The minutes of today's meeting are available for review at [1]. We have
> resolved all but one issue (Implementability for tables w/o primary key)
> which mainly Eric, Richard and Juan are trying to resolve till next week
> over the mailing list.
>
> Cheers,
>           Michael
>
>
> [1] http://www.w3.org/2012/05/01-RDB2RDF-minutes.html
>
>
> The WG has taken the following resolutions at today's call:
>
> ===
> Re: Fixing an omission in R2RML: syntax of blank node labels (
> http://lists.w3.org/Archives/Public/public-rdb2rdf-wg/2012Apr/0060.html):
>
> RESOLUTION: Change Section 11.2 of R2RML
> http://www.w3.org/TR/2012/CR-r2rml-20120223/#generated-rdf-term)  to:
>
> [[
> If the term type is rr:BlankNode: Return a blank node that is unique to
> the natural RDF lexical form corresponding to value.
>
> NOTE: RDF syntaxes and RDF APIs generally represent blank nodes with blank
> node identifiers. But the characters allowed in blank node identifiers
> differ between syntaxes, and not all characters occurring in value may be
> allowed, so a bijective mapping function from values to valid blank node
> identifiers may be required. The details of this mapping function are
> implementation-dependent, and an R2RML processors may have to use different
> functions for
> different output syntaxes or access interfaces. Strings matching the
> regular expression [a-zA-Z_][a-zA-Z_0-9-]* are valid blank node identifiers
> in all W3C-recommended RDF syntaxes.
> ]]
>
>
> ===
> Re: Using non-existing column in mapping (
> http://lists.w3.org/Archives/Public/public-rdb2rdf-wg/2012Apr/0018.html)
>
> RESOLUTION: No change.
>
>
> ===
> Re: Unnamed columns in rr:sqlQuery
> http://lists.w3.org/Archives/Public/public-rdb2rdf-wg/2012Apr/0017.html
>
> RESOLUTION: Change Section 5.2 of the R2RML spec (
> http://www.w3.org/TR/2012/CR-r2rml-20120223/#r2rml-views) to:
>
> [[
> Any columns in the SELECT list derived by projecting an expression SHOULD
> be named.
> ]]
>
>
> ===
> Re: XSD mapping for binary columns (xsd:hexBinary vs. xsd:base64Binary)
> http://lists.w3.org/Archives/Public/public-rdb2rdf-wg/2012Apr/0020.html
>
>
> RESOLUTION: Binary datatypes like BLOB and VARBINARY should be mapped to
> xsd:hexBinary instead of xsd:base64Binary.
>
>
> ===
> Re: DM cannot be implemented as an R2RML mapping (period encoding)
> http://lists.w3.org/Archives/Public/public-rdb2rdf-wg/2012Apr/0021.html
>
> RESOLUTION: The WG agrees to go with
> http://lists.w3.org/Archives/Public/public-rdb2rdf-wg/2012Apr/0070.html
>
>
>
> --
> Dr. Michael Hausenblas, Research Fellow
> DERI - Digital Enterprise Research Institute
> NUIG - National University of Ireland, Galway
> Ireland, Europe
> Tel.: +353 91 495730
> WebID: http://sw-app.org/mic.xhtml#i
>
>
>