- From: Lee Feigenbaum <lee@thefigtrees.net>
- Date: Tue, 09 Feb 2010 05:29:52 -0500
- To: Steve Harris <steve.harris@garlik.com>
- CC: Andy Seaborne <andy.seaborne@talis.com>, "public-rdf-dawg@w3.org Group" <public-rdf-dawg@w3.org>
Steve Harris wrote: > On 9 Feb 2010, at 09:00, Andy Seaborne wrote: >> On 08/02/2010 10:23 AM, Steve Harris wrote: >>> http://www.w3.org/2009/sparql/track/issues/35 >>> Can aggregate functions take DISTINCT as an argument a la SELECT >>> COUNT(DISTINCT ?X)? >>> - Seems consensus on yes. >> >> A URI should name the function, not a collection of related >> functionality. >> >> Example: >> >> COUNT(DISTINCT ?x) vs COUNT(?x) >> >> How do you name the difference if they are not different URIs? > > In my view, DISTINCT does not change the function, it changes the > (multi)set that the function is applied to, c.f. > http://www.w3.org/2009/sparql/docs/query-1.1/rq25.xml#aggregateAlgebra > > More concretely, you form a DISTINCT multiset of the bound values of ?x, > then apply the count function to the resulting set. FWIW, this is exactly how Glitter treats the DISTINCT modifier for both built-in and custom aggregates. It modified the set of solutions passed to the aggregate function. Lee > >> In custom aggregates, what does my:agg name? > > The aggregate function, defined as per the aggregate functions in §9.2. > > - Steve >
Received on Tuesday, 9 February 2010 10:30:29 UTC