- From: Eric Prud'hommeaux <eric@w3.org>
- Date: Tue, 22 Mar 2005 08:59:39 -0500
- To: RDF Data Access Working Group <public-rdf-dawg@w3.org>
- Message-ID: <20050322135939.GD22986@w3.org>
On Tue, Mar 22, 2005 at 10:14:19AM +0000, Steve Harris wrote: > > This is a general comment on feature creep. > > While these are useful features, they are complicated to test, time > consuming to implement, and I dont really want a precident for us adding > every feature that someone requests on the comments list. > > If we carry on at this rate will will end up with something (eventually) > that is essentially SQL for triples, but woefully underspecified. The SQL > '92 spec is large, and still not extensive enough to give real > interoperability between SQL systems. I dont want SPARQL to fall into the > same trap when we have a chance to make a clean start with real > interoperablity. Every complicated feature that gets added coumpunds the > risk that a significant proportion of developers will not support some > part of the specification, preventing interop. > > - Steve +1 I'd like the change the question from "are people going to complain if we don't have this feature?" to "is SPARQL useful to many folks without this feature?". I think the 80/20 rule and "it's version 1" is a perfectly valid response to last call requests for features. > On Mon, Mar 21, 2005 at 04:04:29 +0000, Andy Seaborne wrote: > > > > Matters arising from the comments list: > > > > > > 1/ SELECT to involve expressions > > > > SQL allows constants and expressions in explicit projections (SQL SELECT in > > other words) > > > > SELECT ?x "constant" ... > > SELECT ?x (?x+?y) ... > > > > Combined with nested SELECTs and UNIONs, we would have a way to tag which > > branch of a union a solution came from. This can already be done using > > different variables in each branch. > > > > This would require access to results by column number (or aliases which are > > not required by SQL) and so have impact on the results format. > > > > At the moment, SPARQL UNION is defined without the explicit SELECT > > projection and is a graph pattern operator. There is no no assignment of > > values - it's not possible to return RDF terms that are not in the graph or > > a dataset label. > > > > > > 2/ GROUP BY > > > > Request for SQL-like GROUP BY in addition to ORDER BY. GROUP BY allows the > > application of aggrgeate functions which is more problematic than ORDER BY > > (that only chnages the order of solutions, it does not remove, add or > > change solutions). It's use with aggregation functions like sum(), count() > > that is tricky because of defining what is being counted (names or > > individuals). > > > > COUNT() can lead to a significant decrease in network bandwidth but I have > > not seen a proposal as to what it means for RDF query that explciitly > > addresses the closed world assumptions. > > > > > > Andy > > -- -eric office: +81.466.49.1170 W3C, Keio Research Institute at SFC, Shonan Fujisawa Campus, Keio University, 5322 Endo, Fujisawa, Kanagawa 252-8520 JAPAN +1.617.258.5741 NE43-344, MIT, Cambridge, MA 02144 USA cell: +81.90.6533.3882 (eric@w3.org) Feel free to forward this message to any list for any purpose other than email address distribution.
Received on Tuesday, 22 March 2005 13:59:39 UTC