Set the minimum number of keys that will be stored on any single
This value is used to determine which keys will be stored on overflow
pages, i.e. if a key or data item is larger than the pagesize divided
by the bt_minkey value, it will be stored on overflow pages
instead of in the page itself.
The bt_minkey value specified must be at least 2; if bt_minkey
is not explicitly set, a value of 2 is used.