public void init(TypeInfo[] typeInfos, int[] columnNums) throws HiveException {
    keySerializeRow = new VectorSerializeRow<T>(serializeWrite);
    keySerializeRow.init(typeInfos, columnNums);
    hasAnyNulls = new boolean[VectorizedRowBatch.DEFAULT_SIZE];
  }
A key series of a multiple columns of keys where the keys get serialized.
(Or, it can be 1 column).
ql/src/java/org/apache/hadoop/hive/ql/exec/vector/keyseries/VectorKeySeriesMultiSerialized.java