W3C home > Mailing lists > Public > public-rdf-dawg@w3.org > April to June 2004

RE: Requirement 3.6: Optional Match

From: Rob Shearer <Rob.Shearer@networkinference.com>
Date: Thu, 6 May 2004 12:39:23 -0700
Message-ID: <CFE388CECDDB1E43AB1F60136BEB49730280AE@rome.ad.networkinference.com>
To: "Seaborne, Andy" <andy.seaborne@hp.com>, "RDF Data Access Working Group" <public-rdf-dawg@w3.org>

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.

> -----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 Thursday, 6 May 2004 15:41:53 GMT

This archive was generated by hypermail 2.3.1 : Tuesday, 26 March 2013 16:15:19 GMT