- From: Seaborne, Andy <andy.seaborne@hp.com>
- Date: Wed, 28 Jul 2004 14:13:33 +0100
- To: "Eric Prud'hommeaux" <eric@w3.org>
- Cc: public-rdf-dawg@w3.org
Could this be addressed with a general paramterised queries (see also [1]) mechanism? If CDDB and IMDB were on the same site it would be nice to flow the paramters from the first query to the second without a round trip back to the client. Andy [1] http://lists.w3.org/Archives/Public/public-rdf-dawg/2004JulSep/0090.html Eric Prud'hommeaux wrote: > Joe wants to see what top 10 movies of also had top-ten soundtracks. > IMDB has information about movies and CDDB has info about music. Joe > writes a query that gets the titles of all the top 10 movies. These > are boudn to the variable ?t. He uses those bindings for ?t to then > query IMDB to filter out the ones that did not have top 10 > soundtracks. > > from CDDB: > CONSTRUCT (?t foo bar) > WHERE (?m tt:rank ?rc) > (?m cddb:soundtrack ?s) > (?s dc:title ?t) > AND ?rc <= 10 > > from IMDB: > SELECT ?t > WHERE (?r tt:rank ?ri) > (?r dc:title ?t) > AND ?ri <= 10 > > > This needs the ability to use variables bound in an earlier query to > constrain later queries. It also requires some sort of query > targeting. In algae, this looks like: > > ns tt=<...> > ns cddb=<...> > ns dc=<...> > > attach <http://www.w3.org/...#remoteQuery> ?cddb ( > server=<http://cddb.com/rq>) > ask ?cddb ( ?m tt:rank ?rc {?rc <= 10} . > ?m cddb:soundtrack ?s . > ?s dc:title ?t ) > attach <http://www.w3.org/...#remoteQuery> ?imdb ( > server=<http://imdb.com/querySrvc>) > ask ?cddb ( ?r tt:rank ?ri {?ri <= 10} . > ?r dc:title ?t ) > collect (?t) > > > This is very different from (more rigorous and expensive than) our > current definition of aggregate query [1]. Such a query would, if the > data is divided as the above queries suggest, return zero results. > > [1] http://www.w3.org/2001/sw/DataAccess/UseCases#d4.5
Received on Wednesday, 28 July 2004 09:14:49 UTC