void copyIntoBatch(VectorizedRowBatch destination,
                     VectorizedRowBatch source,
                     int sourceStart) {
    int rows = Math.min(source.size - sourceStart, destination.getMaxSize());
    for(int c=0; c < source.cols.length; ++c) {
      destination.cols[c].reset();
      copyColumn(destination.cols[c], source.cols[c], sourceStart, rows);
    }
    destination.size = rows;
  }
Copy part of a batch into the destination batch.
@param destination the batch to copy into
@param source the batch to copy from
@param sourceStart the row number to start from in the source
@return the number of rows copied
ql/src/java/org/apache/hadoop/hive/ql/io/orc/RecordReaderImpl.java