JN> I did some reading through the mailing list archives and the Elephant JN> manual, but cannot find a recommended way of counting the number of JN> persistent objects of a particular class.
JN> I have a method that works (using map-class) but this is way too slow JN> for my purposes. JN> I did find some postings from Oct last year about this question but no JN> definitive answer it seams. JN> Any advice? as far as i know, most btree implementation do not have a fast way to count leafs -- you need to iterate through all of them. in PostgreSQL (and i think in most relational databases like that) query "SELECT COUNT(*) FROM tree11" takes time proportional to number of elements in tree11. of course it would be much faster to do "SELECT COUNT(*)" then reading all elements on Lisp side, but it will be flawed anyway. so, the advice would be to count this parameter yourself. for example, make btree class-name -> instance count. and update it in initialize-instance (you can move this functionality to some instance-counter-mixin class), and whereever you delete them.. _______________________________________________ elephant-devel site list elephant-devel@common-lisp.net http://common-lisp.net/mailman/listinfo/elephant-devel
