If you REALLY need the count, try SELECT COUNT(...) WHERE..., it will tell you the number of hits.
Some databases promise to guess/estimate the number of the rows in a query result, even though the returned value is grossly incorrect. SESAM does not know the number of rows in a query result before actually fetching them. If you REALLY need the count, try SELECT COUNT(...) WHERE..., it will tell you the number of hits. A second query will (hopefully) return the results.