Re: [rules-users] Drools STREAM Mode performance with rather simple rule

And, I hope, it doesn't matter in which order the Events A with id x are matched with Events B with the same id. The idea of my approach is to make the Events A, B, C not directly visible to the rule ABC but through a "filter" fact, one per type (A, B. C) and per id. Here is the abstract base class for the filter fact; Event is the base class for the three EventA/B/C (or use Object). package event; import java.util.*; public abstract class EventList { private String id; private List<Event> list; public EventList( int id ){ this.id = "" + id; list = new ArrayList<Event>(); } public String getId(){ return id; } public int size(){ return list.size(); } public void add( Event event ){ list.add( event ); } public void delFirst(){ list.remove( 0 ); } } Here is the insertion: long t0 = System.currentTimeMillis(); int limit = 10; EventListA[] aList = new EventListA[limit]; EventListB[] bList = new EventListB[limit]; EventListC[] cList = new EventListC[limit]; int count = 100; for( int i = 0; i < limit; i++ ){ aList[i] = new EventListA( i ); bList[i] = new EventListB( i ); cList[i] = new EventListC( i ); for( int j = 0; j < count; j++ ){ EventA eventA = new EventA( i ); aList[i].add( eventA ); session.insert( eventA ); EventB eventB = new EventB( i ); bList[i].add( eventB ); session.insert( eventB ); EventC eventC = new EventC( i ); cList[i].add( eventC ); session.insert( eventC ); } session.insert( aList[i] ); session.insert( bList[i] ); session.insert( cList[i] ); } session.fireAllRules(); long t1 = System.currentTimeMillis(); System.out.println( "id limit " + limit + ", execution of " + count + " identical triples: " + (double)(t1-t0)/1000.0 ); Here's the rules: rule ABC when $a : EventListA( $aid: id, size > 0 ) $b : EventListB(id == $aid, size > 0 ) $c : EventListC(id == $aid, size > 0 ) then $a.delFirst(); update( $a ); $b.delFirst(); update( $b ); $c.delFirst(); update( $c ); // …(actions) end rule killEmtpyList when $el: EventList( $id : id, size == 0 ) then System.out.println( "retracted " + $el.getClass().getSimpleName() + $id ); retract( $el ); end There are a couple of things to watch out for, and to refine. * You may want to keep track of existing EventListX in maps, or use a couple of rules to create and add new EventX to their EventListX. * Perhaps another collection type is more efficient than ArrayList; depends on how many Xs with identical ids you expect. * make sure to update after EventList.add and .delFirst, also when doing it in Java code. (My insert sequence inserts the completed EventList.) An entirely different approach might be possible using temportal operators, provided the events have distinct timestamps: $a: EventA( $id : id, marked == false ) not EventA( if == $id, this before $a, marked == false ) // same for B, C but here you'll have to retract the "winners" or else mark them as matched. HTH -W 2010/11/15 Roess. Oliver <o.roess(a)seeburger.de&gt;