@Override
  public void seekToRow(long row) throws IOException {
    if (row >= baseRow && row < baseRow + batch.size) {
      rowInBatch = (int) (row - baseRow);
    } else {
      super.seekToRow(row);
      batch.size = 0;
      ensureBatch();
    }
  }
If the current batch is empty, get a new one.
@return true if we have rows available.
@throws IOException
ql/src/java/org/apache/hadoop/hive/ql/io/orc/RecordReaderImpl.java