Tuning Guidelines vis-a-vis SQL_TRACE

Im presently reading a book on SQL Tuning by Guy Harrison. TAlking about the SQL_TRACE parameters the book says that:

1- (Parse count)/(Execute count) must be close to 1 (or else unnecessary parsing is being performed)
2-(Blocks read )/(rows retrieved for execute/fetch/parse) must be less then 10-20 (i dont understand the implication of this) 3-(Rows fetched)/(Fetch Calls) must be close to 10 or 15 (arrray fetching)
4-(Disk reads)/(Logical reads) must be equal to 0.1 (or else cache miss rate is too high)

Could anyone tell me how practical are these statistics? I know its difficult to prophesize exact figures for this but generally speaking how closely do these guidelines represent teh reality.

Anyhow, I think its a great book and strongly recommend to anyone seeking to enter ther realm of SQL tuning.

Thx..

Umar Farooq Ch.
Software Engineer
CresSoft
Lahore, Pakistan. Received on Sat Jun 06 1998 - 06:01:08 CDT