buffer cache hit ration calculation

hello all;

I am preparing for the OCP exam and I have a problem with the buffer cache hit ratio calculation:

1. The OCP DBA Certif Exam Guide by Couchman (ISBN 0-07-882549-0) says on page 875,

cache hit ratio = (Physical Reads/(db block gets + consistent gets)) * 100

2) The Oracle8 Advanced Tuning and Administration by Aronoff, Loney, Sonawalla (ISBN 0-07-882534-2) says on page 45

cache hit ration = ((consistent gets + db block gets - physical gets)/(consistent gets + db block gets)) *100

which one is correct?

Thank you,

Cosmin Received on Thu Dec 23 1999 - 09:45:35 CST