[rules-users] How to make this rule more memory efficient?

Hi, Can anyone advise me on how to make a drools rule more memory efficient? Here is the problem: I have a Cell and a ProxyCell object classes. The ProxyCell represents the Cell when their internal ID's match. Each Cell and ProxyCell however has a unique name (not same as ID). A Cell can reference (by name) a ProxyCell (as long as the ProxyCell does not represent that actual Cell - which would effectively be a self-reference and is not allowed). What I want to do is find out where I have a reference from any instance of Cell - cell1 - to any instance of ProxyCell - proxycell2 - but am missing a reference from cell2 to proxycell1 where proxycell2 is a representation of cell2 and proxycell1 is a representation of cell1. Here is the rule I have written for it: rule "Check consistent references" when $cell1 : Cell() $cell2 : Cell() $proxycell1 : ProxyCell ( id = $cell1.id, $cell2.references contains this.name ) $proxycell2 : ProxyCell ( id = $cell2.id, $cell1.references not contains this.name ) then //report an error..... end I have 10,000 instances of Cell and 10,000 instances of ProxyCell in working memory. For each instance of Cell, it can have references to 60 different ProxyCell instances. Loading the Cell and ProxyCell instances into working memory is not a problem. However, when I try to run this rule above, the memory quickly goes above 1GB and I eventually get an out of memory error. I was wondering if there is a better way to structure or write this rule so that it doesn't use so much memory. Thanks, Ryan.