RE: negative value for buffer cache hit ratio

Thanks a lot , Srini ! I have this feeling too. Unfortunately , bouncing the instance is not an option at the moment (it's up since March , 2001). The other problem is , when i'll restart the instance , the statistics will disappear , so i never know my hit ratio ;-( -Original Message-

RE: negative value for buffer cache hit ratio

Hi Christopher ! SQL select to_char(100 * misses / (hits + misses), '9990.00') || '%' miss_rate 2from ( select total_waits misses 3from sys.v_$system_event 4 where event = 'db file sequential read' ), 5 ( select sum(dbbget + conget - pread)

RE: negative value for buffer cache hit ratio

Hello Jonathan ! Thanks for reply ! First , i love your site and may i recommend it to all the listers : http://www.jlcomp.demon.co.uk/#Index Second, yes , U are right : SQL col HITS for 999,999,999,999,999,999 SQL select sum(dbbget + conget - pread) hits from x$kcbwds 2where inst_id =

RE: negative value for buffer cache hit ratio

recipients of list ORACLE-L Asunto: RE: negative value for buffer cache hit ratio Hi, Generally speaking.. HIT RATIOS does not give the true picture always. I have seen databases performing extremely good with 50% and bad databases with 99% hit ratio. You should never decide the database performance

Re: negative value for buffer cache hit ratio

Interesting. In 8.1.7 32-bit oracle binary, select * from v$type_size where type = 'UB4' tells me it's 4 bytes. So it's 32 bit and the maximum is 4 billion. Glad to see Jonathan on this forum. Yong Huang [EMAIL PROTECTED] you wrote: From: K Gopalakrishnan Welcome Jonathan, I think most

RE: negative value for buffer cache hit ratio

, but there are no wait events then your database does not need tuning. Rachel From: Ramon Estevez [EMAIL PROTECTED] Reply-To: [EMAIL PROTECTED] To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED] Subject: RE: negative value for buffer cache hit ratio Date: Wed, 08 Aug 2001 06:27:11 -0800

RE: negative value for buffer cache hit ratio

. If the cache hit ratio is low, but there are no wait events then your database does not need tuning. Rachel From: Ramon Estevez [EMAIL PROTECTED] Reply-To: [EMAIL PROTECTED] To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED] Subject: RE: negative value for buffer cache hit ratio Date: Wed, 08 Aug

Re: negative value for buffer cache hit ratio

hit ratio is low, but there are no wait events then your database does not need tuning. Rachel From: Ramon Estevez [EMAIL PROTECTED] Reply-To: [EMAIL PROTECTED] To: Multiple recipients of list ORACLE-L [EMAIL PROTECTED] Subject: RE: negative value for buffer cache hit ratio Date: Wed, 08 Aug

RE: negative value for buffer cache hit ratio

Try this more accurate query: select to_char(100 * misses / (hits + misses), '9990.00') || '%' miss_rate from ( select total_waits misses from sys.v_$system_event where event = 'db file sequential read' ), ( select sum(dbbget + conget - pread) hits

RE: negative value for buffer cache hit ratio

Andrey, I am not into cache hit ratios, but got curious about your negative value. So I casually searched Metalink for 'negative value for hit ratio'. And got a hit on 'MROC: I am receiving a negative Buffer Cache hit ratio' thread. You may want to check it out, there seems to be a new

RE: negative value for buffer cache hit ratio

1.- Go to this link of Steve Adam's site: http://www.ixora.com.au/scripts/cache.htm You gonna find a script to estimate the miss rate of the buffer cache based on the assumptions that certain operations are not well compute by statistics as direct path operations. 2.- From 8.X you should rely

RE: negative value for buffer cache hit ratio

Ran this query under 8i(HP-UX 11) SQL show user USER is SYS SQL select to_char(100 * misses / (hits + misses), '9990.00') || '%' miss_rate 2from ( select total_waits misses 3from sys.v_$system_event 4 where event = 'db file sequential read' ), 5

RE: negative value for buffer cache hit ratio

Kirti, Audrey, I was under the impression that negative numbers are caused by the numbers wrapping around i.e., the database has been up for a while and the statistics pile up and eventually exceed the defined format (e.g. value of 1000+ for a format of 9(3) - to use old COBOL representation !).

RE: negative value for buffer cache hit ratio

Nothing is wrong in your database. You don't have the required X_$ views created. Change X_$ to X$ or create X_$ views as select * from X$ views. = Have a nice day !! Best Regards, K Gopalakrishnan, Bangalore, INDIA.

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

RE: negative value for buffer cache hit ratio

I assume you have 8.1.7, since 8.1.7 they changed things back to how it was done in 7.3.4. This script works for 7.3.4 and 8.1.7/9.0.1 select to_char(100 * misses / (logical - physical + misses), '9990.00') || '%' miss_rate from ( select total_waits misses from sys.v_$system_event

Re: negative value for buffer cache hit ratio

Welcome Jonathan, I think most of the counter are limited by ub4maxval and that makes the negative hit ratio. Welcome again ! --- Jonathan Lewis [EMAIL PROTECTED] wrote: It is possible that after 4 months your stats have wrapped around the ( ? 64 bit ?) limit value for your

RE: negative value for buffer cache hit ratio

Christopher Thanks. This script ran from 7.3.4 to 8.1.6 with following result... I hope misses less than 1% is not bad...Any comment SQL select to_char(100 * misses / (logical - physical + misses), '9990.00') || 2 '%' miss_rate 3from ( select total_waits misses 4from

RE: negative value for buffer cache hit ratio

Hi, My misses is MISS_RATE - 0.68% Is that good or bad, Oracle 8.0.5 Standard Edition, Windows 2000. Is there a 8.1.7 Standard Edition Version ? Ramon Estevez [EMAIL PROTECTED] --- Christopher Thanks. This script ran from 7.3.4 to 8.1.6 with following result... I hope misses

RE: negative value for buffer cache hit ratio

Hi, Generally speaking.. HIT RATIOS does not give the true picture always. I have seen databases performing extremely good with 50% and bad databases with 99% hit ratio. You should never decide the database performance based on hit ratio and 90% hit ratio does not mean that 90% of the data is