public static int getRootColumn(boolean isOriginal) {
    return isOriginal ? 0 : (OrcRecordUpdater.ROW + 1);
  }
Get the root column for the row. In ACID format files, it is offset by
the extra metadata columns.
@param isOriginal is the file in the original format?
@return the column number for the root of row.
ql/src/java/org/apache/hadoop/hive/ql/io/orc/OrcInputFormat.java