@Override
  public String toString() {
    return getClass().toString()
        + "["
        + Arrays.asList(serdeParams.getSeparators())
        + ":"
        + ((StructTypeInfo) serdeParams.getRowTypeInfo())
            .getAllStructFieldNames()
        + ":"
        + ((StructTypeInfo) serdeParams.getRowTypeInfo())
            .getAllStructFieldTypeInfos() + "]";
  }
ColumnarSerDe is used for columnar based storage supported by RCFile.
ColumnarSerDe differentiate from LazySimpleSerDe in:<br>
(1) ColumnarSerDe uses a ColumnarStruct as its lazy Object <br>
(2) ColumnarSerDe initialize ColumnarStruct's field directly. But under the
field level, it works like LazySimpleSerDe<br>
serde/src/java/org/apache/hadoop/hive/serde2/columnar/ColumnarSerDe.java