PhysicalPlan ldGrpChain2 = GenPhyOp.loadedGrpChain();
php.merge(ldGrpChain1);
php.merge(ldGrpChain2);
POUnion un = GenPhyOp.topUnionOp();
php.addAsLeaf(un);
PhysicalPlan ldFil1 = GenPhyOp.loadedFilter();
PhysicalPlan ldFil2 = GenPhyOp.loadedFilter();