public void onMatch(RelOptRuleCall call) { JoinRel join = (JoinRel) call.rels[0]; List<RexNode> expList = new ArrayList<RexNode>(Arrays.asList(join.getChildExps())); if (reduceExpressions(join, expList)) { call.transformTo( new JoinRel( join.getCluster(), join.getLeft(), join.getRight(), expList.get(0), join.getJoinType(), join.getVariablesStopped())); // New plan is absolutely better than old plan. call.getPlanner().setImportance(join, 0.0); } }