}
public final static List<IAlgebraicRewriteRule> buildCondPushDownRuleCollection() {
List<IAlgebraicRewriteRule> condPushDown = new LinkedList<IAlgebraicRewriteRule>();
condPushDown.add(new PushSelectDownRule());
condPushDown.add(new InlineVariablesRule());
condPushDown.add(new FactorRedundantGroupAndDecorVarsRule());
condPushDown.add(new EliminateSubplanRule());
return condPushDown;
}