- From: Birte Glimm <birte.glimm@comlab.ox.ac.uk>
- Date: Tue, 1 Mar 2011 13:59:54 +0000
- To: Steve Harris <steve.harris@garlik.com>
- Cc: SPARQL Working Group <public-rdf-dawg@w3.org>
- Message-ID: <AANLkTi=02J=cvodYATaZQtwaE-LyDA6P+zx8Mmn-ZEba@mail.gmail.com>

Hi Steve, I have some comment for the updaed version too (see below). I still would prefer 11.6 to have a more complete example, e.g., showing the query which required the agrregate join. Birte 11.3 ... >HAVING expressions there is an extra > now 11.6 ...evaluating the Aggregate function*s* which share a key. 11.7 Note that the *bindgins* <y> should probably be <http://example.com/data/#y> or :y (if abbreviated) On 28 February 2011 23:04, Steve Harris <steve.harris@garlik.com> wrote: > Thanks Birte, that's very helpful. > > I've just committed version 1.212 which addresses these problems. > > I've also added an example showing how error are handled, and fixed some > more typographical errors. > > - Steve > > On 2011-02-25, at 22:06, Birte Glimm wrote: > > > Steve, others, > > I have now reviewed Section 11 (Aggregates) and I attach my comments > below. Mostly there are some typos and smaller corrections, but I can't make > sense out of 11.6. I gues at least an example is need and probably a bit of > text to put that subsection into context. > > Best regards, > > Birte > > > > 11 Aggregates > > ... > > Aggregates are used where the querier wishes to see a result which is > > compute*d* (not computer) > > > > 11.1 > > ... > > In aggregate queries and sub-queries variables that appear in the query > > pattern, but are not grouped by ... > > "not grouped by" sounds a bit strange to me, I would prefer just "but > > are not grouped" or "but not in the GROUP BY clause" > > > > "It should be noted that <link>as per functions</link>, aggregate > expressions must > > be alised inorder to project them from queries or subqueries. In the > > example obove this is done using the variable ?totalPrice. It is an > > error for aggregates to project variables with a name already used in > > other aggregate projections." > > > > For me the link does not work. > > Should "alised" be aliased? > > obove <- above > > > > 11.2 > > ... > > "Within GROUP BY clases the assignment keyword, AS, may be used. Such > > as GROUP BY (?x + ?y AS ?z). " > > clases <- clauses > > Such as... Is not really a complete sentence and rather belongs to the > previous > > sentence. > > > > ... > > "We can then Apply the set function Avg() to the group solutions, using > the Aggregation() algebra function, as Aggregation((?y), Avg, {}, G), > giving:..." > > apply (lowercase) > > I wondered what the empty set in the Aggregation() algebra function > > was, but in order to get any clues, one has to click on the link and > > read the algebra section. Maybe one can shortly comment on that > > already informally in Section 11.2 or choose an example that also uses > > that feature? > > > > 11.4 > > ... > > "Note that it would not be legal to project STR(?z) as this is not a > > simple variable expression." > > I guess it would be legal to select ?newZ if I were to use (STR(?z) AS > > ?newZ) right? If so, it would be nice to point that out too. > > > > "Other expresisons, not using GROUP BY variables, or aggregates may have > non-deterministic values projected from their groups using the SAMPLE() > aggeregate." > > aggeregate <- aggregate > > > > 11.5 > > "The set functions which underlie SPARQL aggregates all have a common > > signature: SetFunc(M, err), or SetFunc(M, err, scalarvals, ...) where M > is a > > multiset of lists, err is a value indicating whether the evaluation of > any of the > > expressions evaluated with respect to Ω " > > Here we have scalarvals again, so it might really be helpful to say a > > bit about that in the example in 11.2. Also I find Sigma a bit out of > > ontext here, it's the first time used in this section. Could the text > > not just say "a solution sequence"? > > > > "The name is retained due to the comonality with SQL Set Functions, > > which also operate over multisets." > > commonality > > > > "... Systems may choose to expand this set with *local using extensions*, > using the same notation as for functions and casts. " > > local extensions? > > > > 11.6 > > "In order to project values from (sub-)queries using aggregate values, > > a Solution Multiset is constructed where each solution comprises the > > results of the Aggregate functions which share a key." > > Why upper case Solution Multiset and Aggregate functions? > > > > I can't really make sense out of that section. Maybe an example would > > help, but I neither see in what context I would need such aggregate > > joins nor how a query would look like that uses/requires this feature. > > > > > > -- > > Dr. Birte Glimm, Room 309 > > Computing Laboratory > > Parks Road > > Oxford > > OX1 3QD > > United Kingdom > > +44 (0)1865 283520 > > -- > 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 > > -- Dr. Birte Glimm, Room 309 Computing Laboratory Parks Road Oxford OX1 3QD United Kingdom +44 (0)1865 283520

Received on Tuesday, 1 March 2011 14:00:28 UTC