> -----Original Message----- > From: Orri Erling [mailto:[EMAIL PROTECTED] > Sent: 12 August 2008 09:54 > To: Seaborne, Andy; 'Chris Bizer'; [email protected] > Subject: RE: BSBM With Triples and Mapped Relational Data in Virtuoso > > > > Andy >
> We have something of the sort on the SQL side, called a procedure view. MS > SQL Server calls such a thing a table valued function. Anyway, it makes a > result set and can take parameters that give a fixed value to some of the > result columns. Then there is a cost model hookthat allows specifying what > cardinality and cost implications binding or not binding a result column may > have. > > This is quite complex and general agreement would seem improbable to me. > > Please send a link to a description of how Arq addresses functions in > queries. It is in principle possible that we could implement a compatible > syntax, for example on top of the aforementioned procedure views if the > functionality is close. (catching up ...) This is related to a discussion in sparql-dev where I described the ARQ mechanism for something like table valued functions (not identical): http://lists.w3.org/Archives/Public/public-sparql-dev/2008JulSep/0036.html So yes and no. It's improbable that a common interface to the implementation of custom functions but I can see that agreement on syntax and semantics on the side of the way it is expressed in a future SPARQL which helps the application writer if not the custom function implementer. Andy
