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Home -> Community -> Mailing Lists -> Oracle-L -> 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
>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-lReceived on Sat Oct 27 2007 - 06:23:34 CDT
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