@Override
 public PhysicalOperator visitFilter(Filter filter, Object obj) throws OptimizerException {
   TypeProtos.MajorType.Builder b =
       TypeProtos.MajorType.getDefaultInstance().newBuilderForType();
   b.setMode(DataMode.REQUIRED);
   b.setMinorType(MinorType.BIGINT);
   PhysicalOperator child = filter.iterator().next().accept(this, obj);
   return new SelectionVectorRemover(
       new org.apache.drill.exec.physical.config.Filter(child, filter.getExpr(), 1.0f));
 }