- From: Birte Glimm <birte.glimm@comlab.ox.ac.uk>
- Date: Fri, 4 Mar 2011 15:18:27 +0000
- To: Steve Harris <steve.harris@garlik.com>
- Cc: SPARQL Working Group <public-rdf-dawg@w3.org>
- Message-ID: <AANLkTikA+8PYUEkPxwpKkUVyfZCfH_N8W_rxVsUz2uep@mail.gmail.com>
Hi Steve all, just to say that I am happy now with the section and consider my review of that section done. Birte On 2 March 2011 10:07, Steve Harris <steve.harris@garlik.com> wrote: > Hi Birte, > > On 2011-03-01, at 13:59, Birte Glimm wrote: > > 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. > > > All queries require AggregateJoin, it's used to turn the grouped solution > sequence as used by aggregates, into a solution sequence that can be > projected etc. I added a line of text to hopefully make this clearer, but > it's a complex section, so easy to miss. > > "This is required to transform the aggregates solution multisets into > solution multisets as used in the rest of the algebra." > > 11.3 > ... > >HAVING expressions > there is an extra > now > > > Fixed. > > 11.6 > ...evaluating the Aggregate function*s* which share a key. > > > Changed to "evaluating the Aggregate expressions which share a key", as I > think that's probably clearer. > > 11.7 > Note that the *bindgins* > <y> should probably be <http://example.com/data/#y> or :y (if abbreviated) > > > Those have been fixed. > > Thanks, > Steve > > 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 > > > -- > 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 Friday, 4 March 2011 15:19:00 UTC