[rules-users] Memory requirements for "working memory"

Hello All, We are planning to use a rules engine (specifically JBoss rules) for our application which can potentially have upto 1,000,000 facts to crunch through, which can take up a lot of memory. I am interested in any techniques that could be used to reduce memory footprint while holding large number of facts in working memory. Also, our requirements dictate that we maintain a stateful working memory. One thing hat comes to my mind is to demand-fetch field values for java objects at get*() methods on fact objects are invoked, but if rules are touching most of the fields of the facts, then memory would be filled up sooner or later anyway. I know the question is not directly related to JBoss rules, so I apolagize if this is not the appropriate forum to pose this question... Thanks Jeevan