Tell the cursor to continue issuing callbacks when data is available. This is the standard
"I'm ready for more" response. If cursor is not completely drained of all ready results the
callback will be called again immediately.
DONE
Tell the cursor you are done receiving results, even if there are more results sitting in the
buffer. Once you return DONE, you will receive no further callbacks.
Approximately equivalent to calling RowCursor#cancel(), and then returning
PAUSE, but more clear, immediate, and idiomatic.
It is legal to commit a transaction that owns this read before actually returning
DONE.
PAUSE
Tell the cursor to suspend all callbacks until application calls RowCursor#resume().
