When Derby retrieves data from a conglomerate, it can fetch more than one row at a time. Fetching more than one row at a time is called bulk fetch. By default, Derby fetches 16 rows at a time.
Bulk fetch is faster than retrieving one row at a time when a large number of rows qualify for each scan of the table or index. Bulk fetch uses extra memory to hold the pre-fetched rows, so it should be avoided in situations in which memory is scarce.
SELECT * FROM Flights WHERE miles > 4 SELECT * FROM Flights
The default size for bulk fetch (16 rows) typically provides good performance.