It would be nice if the possible arguments to --syntax were listed on the wiki page for tdbquery
On Thu, Jan 6, 2011 at 2:06 PM, Andy Seaborne <[email protected]> wrote: > > > On 06/01/11 18:47, Benson Margulies wrote: >> >> In my store I have (for purposes of discussion) >> >> one tuple S P O >> >> and then some number of quadlets on it. >> >> I want to find out how many. > > SELECT (Count(*) AS ?C) > { > ?x rdf:subject S . > ?x rdf:predicate P . > ?x rdf:object O . > } > > which assumes fully reified. > >> However, to make matters more complex, what I'd really like to do is >> set up a construct query that finds >> >> >> S (p1|p2|p3|p4...) O > > SELECT (Count(*) AS ?C) > { > ?x rdf:subject S . > ?x rdf:predicate ?P . > ?x rdf:object O . > FILTER ( ?P IN ( p1, p2, p3, p4) ) > } > > >> and also then returns the count of quadlets for each of these it comes up >> with. > > Finding then counting, and finding and returning needs duplication of the > thing. It's a quirk in the whole relation algebra thing - you can't assign > subexpressions and reuse them - this is not unique to SPARQL. To look at it > another way, counting is destructive on the things being counted. > >> Is this plausible .... ? Obviously, I can do it by first finding the >> statements and then going back and using the COUNT extension to do the >> counting. > > COUNT isn't an extension - it's part of SPARQL 1.1 > >> Is TDB particularly good or bad at this? > > It does not anything special but caching is your friend (and mime). > > Andy >
