@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));
 }
  /**
   * Creates a copier that does a project for every Nth record from a VectorContainer incoming into
   * VectorContainer outgoing. Each Ordering in orderings generates a column, and evaluation of the
   * expression associated with each Ordering determines the value of each column. These records
   * will later be sorted based on the values in each column, in the same order as the orderings.
   *
   * @param sv4
   * @param incoming
   * @param outgoing
   * @param orderings
   * @return
   * @throws SchemaChangeException
   */
  private SampleCopier getCopier(
      SelectionVector4 sv4,
      VectorContainer incoming,
      VectorContainer outgoing,
      List<Ordering> orderings,
      List<ValueVector> localAllocationVectors)
      throws SchemaChangeException {
    final ErrorCollector collector = new ErrorCollectorImpl();
    final ClassGenerator<SampleCopier> cg =
        CodeGenerator.getRoot(SampleCopier.TEMPLATE_DEFINITION, context.getFunctionRegistry());

    int i = 0;
    for (Ordering od : orderings) {
      final LogicalExpression expr =
          ExpressionTreeMaterializer.materialize(
              od.getExpr(), incoming, collector, context.getFunctionRegistry());
      SchemaPath schemaPath = SchemaPath.getSimplePath("f" + i++);
      TypeProtos.MajorType.Builder builder =
          TypeProtos.MajorType.newBuilder()
              .mergeFrom(expr.getMajorType())
              .clearMode()
              .setMode(TypeProtos.DataMode.REQUIRED);
      TypeProtos.MajorType newType = builder.build();
      MaterializedField outputField = MaterializedField.create(schemaPath, newType);
      if (collector.hasErrors()) {
        throw new SchemaChangeException(
            String.format(
                "Failure while trying to materialize incoming schema.  Errors:\n %s.",
                collector.toErrorString()));
      }

      ValueVector vector = TypeHelper.getNewVector(outputField, oContext.getAllocator());
      localAllocationVectors.add(vector);
      TypedFieldId fid = outgoing.add(vector);
      ValueVectorWriteExpression write = new ValueVectorWriteExpression(fid, expr, true);
      HoldingContainer hc = cg.addExpr(write);
      cg.getEvalBlock()._if(hc.getValue().eq(JExpr.lit(0)))._then()._return(JExpr.FALSE);
    }
    cg.rotateBlock();
    cg.getEvalBlock()._return(JExpr.TRUE);
    outgoing.buildSchema(BatchSchema.SelectionVectorMode.NONE);
    try {
      SampleCopier sampleCopier = context.getImplementationClass(cg);
      sampleCopier.setupCopier(context, sv4, incoming, outgoing);
      return sampleCopier;
    } catch (ClassTransformationException | IOException e) {
      throw new SchemaChangeException(e);
    }
  }