public List<ColumnVector> getColumnVectors(int colIx) {
      if (!hasVectors(colIx)) throw new AssertionError("No data for column " + colIx);
      return columnVectors[colIx];
    }
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