[rules-users] 14GB of NotNodeLeftTuples produced by one rule?

Hi all, we observe a strange behavior with one of our rules. After deployment and sending lots of events (~150,000 of type "a"), the server slows down rapidly until it runs out of memory. We checked with VisualVM which objects are filling the memory: In one moment there were almost 14GB of NotNodeLeftTuples (88,933,186 Instances)! This is our rule: rule "example" when $evt1:EventObject(type=='a', $id:data['id'], $user:user) from entry-point internalstream $evt2:EventObject(type=='a', data['id']==$id, user!=$user, $user2:user) from entry-point internalstream not(EventObject(type=='b', user==$user, data['friendid']==$user2) from entry-point internalstream) then EventObject evt = new EventObject(); evt.setType('b'); evt.setUser($evt1.getUser()); evt.put('friendid', $evt2.getUser()); entryPoints['internalstream'].insert(evt); end Is that behavior correct for such a size of event combinations when using a NOT in the rule? Thanks, Svenja