public static ColumnVector createColumnVector(String typeName,
      DataTypePhysicalVariation dataTypePhysicalVariation) {

    typeName = typeName.toLowerCase();

    // Allow undecorated CHAR and VARCHAR to support scratch column type names.
    if (typeName.equals(serdeConstants.CHAR_TYPE_NAME) || typeName.equals(serdeConstants.VARCHAR_TYPE_NAME)) {
      return new BytesColumnVector(VectorizedRowBatch.DEFAULT_SIZE);
    }

    TypeInfo typeInfo = (TypeInfo) TypeInfoUtils.getTypeInfoFromTypeString(typeName);
    return createColumnVector(typeInfo, dataTypePhysicalVariation);
  }
Reduce the batch size for a vectorized row batch
ql/src/java/org/apache/hadoop/hive/ql/exec/vector/VectorizedBatchUtil.java