Note the following rules:

    o  Oracle Rdb does not guarantee the order of records in a record
       stream unless you specify a sort order. For this reason, when
       you use FIRST n in the RSE, the actual records in the record
       stream are unpredictable. Therefore, you should always specify
       SORT when you use FIRST n.

    o  If n evaluates to zero or a negative number, the record stream
       will be empty.

    o  If you specify FIRST n and n is greater than the number
       of records satisfying those conditions, the record stream
       consists of all records meeting the conditions of the record
       selection expression.

    o  If n is not an integer, Oracle Rdb rounds any fractional part
       of the value and uses the remaining integer as the number of
       records in the record stream.