This is a hint that can be passed to the JDBC driver as to how many rows to fetch from the database at a time.
This is ONLY A HINT to the JDBC driver. It may not even be required very often (it may be required on Postgres for large queries though).
I have added a setBufferFetchSizeHint(int bufferFetchSizeHint) method ...
... to the Query and SqlQuery objects.
This is fixed in HEAD.