Exact equivalent of mysql_data_seek() in PEAR DB

I note that PEAR DB added, quite some time ago, a second optional parameter to the fetchRow() method of DB_result to fetch a specific row by number. But that method advances the result pointer to the next row. That's not how mysql_data_seek() works, which establishes the result pointer at the given row, but does not advance it. I have been using the data_seek() method of the mysqli libraries, but have now converted to PEAR DB. Unfortunately, I have a need to set the result point to 0, and _THEN_ iterate through each of the rows from the first to the last. How do I do that in PEAR DB??? Christopher