Re: negative value for buffer cache hit ratio

It is possible that after 4 months your stats have wrapped around the ( ? 64 bit ?) limit value for your platform. Check the actual values from v$sysstat to see if some of them have gone negative or appear to be
'counting backwards'.

Jonathan Lewis

Seminars on getting the best out of Oracle Last few places available for Sept 10th/11th See http://www.jlcomp.demon.co.uk/seminar.html

-----Original Message-----
To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com> Date: 07 August 2001 19:52

|
|Dear gurus !
|I have a negative value for buffer cache hit ratio in my DB which is
up for
|some 4 months .
|Any ideas why ?
|Thanks in advance.
|
|SQL> SELECT (1 - (SUM(DECODE(a.name,'physical reads',value,0)) /
| 2 (SUM(DECODE(a.name,'consistent gets',value,0)) +
| 3 SUM(DECODE(a.name,'db block gets',value,0))))) * 100 "buffer
cache hit
|ratio"
| 4 FROM v$sysstat a;
|
|buffer cache hit ratio
|----------------------
| -52.99284
|
|--
|Please see the official ORACLE-L FAQ: http://www.orafaq.com
|--
|Author: Andrey Bronfin
| INET: andreyb_at_elrontelesoft.com
|
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-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.com
-- 
Author: Jonathan Lewis
  INET: jonathan_at_jlcomp.demon.co.uk

Fat City Network Services    -- (858) 538-5051  FAX: (858) 538-5051
San Diego, California        -- Public Internet access / Mailing Lists
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