- From: Seaborne, Andy <andy.seaborne@hp.com>
- Date: Fri, 7 May 2004 14:01:18 +0100
- To: Rob Shearer <Rob.Shearer@networkinference.com>, RDF Data Access Working Group <public-rdf-dawg@w3.org>
-------- Original Message -------- > From: Rob Shearer <mailto:Rob.Shearer@networkinference.com> > Date: 6 May 2004 20:39 > > I'm afraid I can't really support this as a requirement, although I > think features which allow this result (albeit not necessary directly) > would almost certainly be extremely useful. > > The thing is, "optional bindings" are really nothing more than unions > between independent queries: union the results of the query with the > binding with the results of the query without it. I'd say a more > general-purpose "union" operator is quite a bit more > important than this > one particular form, and even then I'm not sure whether it > rises to the > level of requirement. Expressing it as "Optional Matching" makes it more user-centric. It covers features that are being requested by users (application writers). Getting AB? (where A and B are graph patterns, ? is 0 or 1) as union(A, AB) might be OK but as the choices grow we get: AB?C? = union(A, AB, AC, ABC) Andy > > > -----Original Message----- > > From: public-rdf-dawg-request@w3.org > > [mailto:public-rdf-dawg-request@w3.org] On Behalf Of Seaborne, Andy > > Sent: 06 May 2004 08:40 To: RDF Data Access Working Group > > Subject: Requirement 3.6: Optional Match > > > > > > > > I suggest what I think are small changes: > > > > + including the term "graph pattern" as is in the suggested > > text for 3.1. > > + tweaking the title > > + Be neutral to "optional triples" and "may-bind" variables. > > > > ------------------------ > > > > 3.6 Optional Matching > > > > It must be possible to express a query graph pattern that > > does not fail to > > match when some nominated part of the graph pattern fails to > > match. Any > > such triples matched by this optional part, or variable > > bindings caused by > > this optional part, can be requested in the results. > > > > ------------------------ > > > > Andy > > > > > > > > > > For reference, the text in v1.39 is: > > """ > > 3.6 Optional Match > > It must be possible to express a query that does not fail when some > > nominated part of the query specifying "optional triples" > > fails to match. > > Any such triples matched by this optional part, or variable bindings > > caused by this optional part, can be returned in the results, if > > requested. """
Received on Friday, 7 May 2004 09:01:48 UTC