@SuppressWarnings("unchecked")
    public void initColumnWithVectors(int colIx, List<ColumnVector> data) {
      if (columnVectors == null) {
        columnVectors = new List[columnData.length];
      }
      columnVectors[colIx] = data;
    }
Same as columnData, but for the data that already comes as VRBs.
The combination of the two contains all the necessary data,
ql/src/java/org/apache/hadoop/hive/ql/io/orc/encoded/Reader.java