Thanks a lot , we really got what we want. On Wed, Dec 23, 2009 at 4:53 AM, Alex Mizrahi <killerst...@newmail.ru>wrote:
> > 2. What we have decided is to make separate persistent class for each > > predicate. > > So, class is a predicate, right? > > >3. (defpclass dependson () > > ((subject :accessor subject) > > (predicate :accessor predicate) > > (object :accessor object))) > > Why do you need a predicate slot then? Predicate for dependson class is > dependson. > > > 4. How do I index a slot so that later if I have a query where I have > been > provided with two slot values I should be able to get the third slot value. > For example: Force-dependson-? should return "mass" and "acceleration". > > Elephant implements (on a low level) key-value pair store rather than a > triple store. > If you want a triple store, there are basically two way to do it -- either > use > compound keys, e.g. (subject, predicate)->object. > Or use nested key-value stores, something like > subject->(predicate->object). > > Class-per-predicate essentially implements later approach with nested > key-value stores -- because each class in Elephant has its own btrees > for indices. > > So, just use get-instances-by-value. Like > > (ele:get-instances-by-value 'dependson 'object value) > > or > > (ele:get-instances-by-value 'dependson 'subject value) > > Pretty obvious, no? > Either you've got confused by your own constructs, or I've misunderstood > something. > > > > > > _______________________________________________ > elephant-devel site list > elephant-devel@common-lisp.net > http://common-lisp.net/mailman/listinfo/elephant-devel >
_______________________________________________ elephant-devel site list elephant-devel@common-lisp.net http://common-lisp.net/mailman/listinfo/elephant-devel
