- From: Steve Harris <S.W.Harris@ecs.soton.ac.uk>
- Date: Mon, 7 Mar 2005 14:25:01 +0000
- To: "'RDF Data Access Working Group'" <public-rdf-dawg@w3.org>
On Sun, Mar 06, 2005 at 04:58:16 +0000, Andy Seaborne wrote: > == 4 == Syntactic support for reification > > Some people use reification and use it a lot - some people use named > graph-like approaches and avoid reification - most people just don't use > either. The others seem good, and I have no opinion on this... > == 5 == Sorting/Grouping > > A request for SQL-like facilities to control the presentation of result > sets. It makes testing interesting - sometimes unordered is acceptable and > sometimes it's (partially) not. > > There are issues around defining the ordering between unrelated things like > strings and URIs, bNodes and integers, dates and doubles - would need some > arbitrary decisions. Not clear to me that it could be pushed into SQL > sorting for the semi-structued cases - in SQL, the engine knows the column > type. I think we allready discussed this and decided it was too much work to specify at this stage. I have uses for sorting, though I'm not sure any of my users do, so leaving it for now is fine by me. I dont think theres consensus on how it should work. > The decision would seem to be as much WG time as anything else. I suppose > that we could reserve syntax without defining semantics in tests at this > stage but that isn't very helpful to interoperability/ Its not worked very well for SQL. > == 6 == Optionals and order dependencies. > > The alternatives I think if or know about are (briefly): > > A/ An order rule that states variables must be used in fixed > patterns before optionals if possible. We can either make > a query that does not do this illegal, execute in this > canonical order or leave to implementations. I have a preference for this. Currently I process all the non-OPTIONAL blocks, then all the optionals in order, so I have a preference for doing that :) - Steve
Received on Monday, 7 March 2005 14:45:54 UTC