Certain statements and fields automatically exclude a query from consideration for a firehose or firehose block cursor. For example:
FOR FIRST and
FOR LAST statements. These statements return at most one row, so they are optimized with the Transact-SQL keyword
TOP, which renders them ineligible for a firehose cursor.
When the DataServer is unable to implement Firehose or Firehose block cursors, the server-side Fast Forward-only (FFO) cursors are implemented. For information about FFO cursors, see
FastForward-Only cursors.
