RE: prefixed index - high clustering factor & high cpu


Please supply the tkprof output you are using to get these figures.

Is your "cost about 30k" from the Rowsource Operation output,
showing "time = 30000 microseconds" ?  Or is it actually from
a plan_table.

If the latter, then a CPU cost of around 30,000 (Oracle operations)
is perfectly reasonable for 4 buffer visits to acquire a single row by
unique index.


Regards

Jonathan Lewis
http://jonathanlewis.wordpress.com

Author: Cost Based Oracle: Fundamentals
http://www.jlcomp.demon.co.uk/cbo_book/ind_book.html

The Co-operative Oracle Users' FAQ
http://www.jlcomp.demon.co.uk/faq/ind_faq.html


----- Original Message -----
Subject: RE: prefixed index - high clustering factor & high cpu

at the tkprof the cpu cost is very high , its about 30k, rows returned
is 1 , io cost is 4 , the cost itself only 4.

--
http://www.freelists.org/webpage/oracle-l


Other related posts: