- From: Juan Sequeda <juanfederico@gmail.com>
- Date: Tue, 1 May 2012 13:55:51 -0500
- To: Michael Hausenblas <michael.hausenblas@deri.org>
- Cc: W3C RDB2RDF <public-rdb2rdf-wg@w3.org>
- Message-ID: <CAMVTWDzk9kCsv3g1Ph=7zSrhg6A-cs1wDgYMw=6CHzT98ogXMw@mail.gmail.com>
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 > > >
Received on Tuesday, 1 May 2012 18:56:41 UTC