I think you have been a bit short in the problem description.

You just meant that all the requested data is already in buffer and no physical read is needed. Thanks but we have no information on the nature of the sql, the amount of data, the expected goal. Bad or good SQL is a ratio of  these. What if I read one million blocks from my multi gig db block buffer to return a tiny rowset for the worse ever seen SQL,  it will satisfy your prerequisite and still be very bad.

B.Polarski
http://www.smenu.org