- From: Steve Harris <steve.harris@garlik.com>
- Date: Fri, 13 Aug 2010 15:55:43 +0100
- To: Axel Polleres <axel.polleres@deri.org>
- Cc: SPARQL Working Group <public-rdf-dawg@w3.org>, Andy Seaborne <andy.seaborne@epimorphics.com>, Paul Gearon <gearon@ieee.org>
On 2010-08-13, at 13:16, Axel Polleres wrote: ... >>> True, indeed, it would need subqueries allowed in IN in FILTERS with the mentioned behavior, i.e. >>> that existing bindings are "injected" in the FILTER before the subquery is evaluated. >> >> Right, which would mean that part of our algebra as top-down, and part bottom-up. > > Hmmm, which is something we partially have already with FILTERs in OPTIONALs...? A OPTIONAL { B . FILTER(C) } is defined as LeftJoin(A, B, C). C can't contain any bottom-up expressions, as os SPARQL 1.0. >> I suspect it would be very hard to specify that without introducing non-deterministic results. > > As long as this only affected subqueries in FILTER evaluation (which though - admittedly - would imply reopening ISSUE-6), > I can't see a big problem. As I said, aren't FILTERs already supposed to be evaluated only after replacement of the variables? Yes, but the algebra is not. > I am trying to sum up: > > On the one hand, the specific use case might be viewed as new information, so it might be > ok to reopen issues, such as ISSUE-6. We already knew this particular usecase was going to be tricky/verbose, when it was discussed with subquery syntax. so it's not new information. My feeling is much like Paul's. I think we don't have enough time to finish what we have on our plate now, without bringing in new use-cases. - Steve -- Steve Harris, CTO, Garlik Limited 1-3 Halford Road, Richmond, TW10 6AW, UK +44 20 8439 8203 http://www.garlik.com/ Registered in England and Wales 535 7233 VAT # 849 0517 11 Registered office: Thames House, Portsmouth Road, Esher, Surrey, KT10 9AD
Received on Friday, 13 August 2010 14:56:24 UTC