- From: Steve Harris <swh@ecs.soton.ac.uk>
- Date: Sun, 4 Nov 2007 13:29:26 +0000
- To: Alan Ruttenberg <alanruttenberg@gmail.com>
- Cc: public-sparql-dev@w3.org
Not all subqueries have an equivalent, at least not in SQL. - Steve On 4 Nov 2007, at 13:05, Alan Ruttenberg wrote: > Is there a reason one would like to do a local subquery? Isn't it > equivalent to something that you could write at top level with about > the same number of characters? > > -Alan > > On Nov 4, 2007, at 7:55 AM, Steve Harris wrote: > >> Well, that would be the obvious syntax for a local sub-query too. >> >> - Steve >> >> On 4 Nov 2007, at 12:48, Alan Ruttenberg wrote: >> >>> Although I intended that the specification of this was that it was >>> only legal for an endpoint, as that's what makes it easy. I'm not >>> sure it's a useful construct otherwise, as you don't need it >>> nested in the FROM if you have to download the file. >>> -Alan >>> >>> >>> On Nov 4, 2007, at 7:38 AM, Alan Ruttenberg wrote: >>> >>>> Good point. Perhaps FROM ENDPOINT. >>>> >>>> -Alan >>>> >>>> On Nov 4, 2007, at 7:35 AM, Steve Harris wrote: >>>> >>>>> On 4 Nov 2007, at 04:09, Alan Ruttenberg wrote: >>>>> >>>>>> This is a particularly easy one, since it adds no new >>>>>> expressivity. The form >>>>>> below can be syntactically transformed into SPARQL as specified >>>>>> now by way >>>>>> of using the SPARQL protocol for the construct in the FROM. >>>>>> Since this is the only reasonable way we have to do federation >>>>>> now, within >>>>>> spec, it's more like adding friendly syntactic sugar. >>>>> >>>>> As far as I can tell there's no way to tell that <http://example.com/sparql? >>>>> > is a SPARQL endpoint, rather that a graph served by a CGI >>>>> script with no arguments. >>>>> >>>>> - Steve >>>>> >>>>>> On 11/3/07, Dan Connolly <connolly@w3.org> wrote: >>>>>>> >>>>>>> Alan Ruttenberg wrote: >>>>>>>> >>>>>>>> SELECT ?a ?b >>>>>>>> FROM ( CONSTRUCT { ?d <b> ?b } >>>>>>>> FROM < http://example.com/sparql?> >>>>>>>> WHERE { ?b <b> ?d } ) >>>>>>>> WHERE { ?a <b> ?b } >>>>>>> >>>>>>> >>>>>>> Yes... the Data Access WG considered this sort of thing briefly; >>>>>>> we didn't see any particular reason not to do it but we... >>>>>>> >>>>>>> RESOLVED 2005-01-20: to postpone cascadedQueries; while >>>>>>> federation use >>>>>>> cases are interesting, the designs don't seem mature and the >>>>>>> use cases >>>>>>> are not urgent; with KendallC abstaining. >>>>>>> http://www.w3.org/2001/sw/DataAccess/issues#cascadedQueries >>>>>>> >>>>>>> I'm happy to see people playing around with it; I hope the >>>>>>> designs get mature soonish. >>>>>>> >>>>>>> >>>>>>> -- >>>>>>> Dan Connolly, W3C http://www.w3.org/People/Connolly/ >>>>>>> >>>>>>> >>>>> >>>> >>> >> >
Received on Sunday, 4 November 2007 13:30:00 UTC