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Negative Values of Library Cache Hit Ratio in AWR Report [message #562131] Sun, 29 July 2012 03:34 Go to next message
mail.madhankumar
Messages: 11
Registered: July 2012
Location: coimbatore
Junior Member
Hi Friends,
We are getting Negative values of Library cache hit ratio in AWR Report of 11g(11.2.0.3) with Solaris[tm] OE (64-bit).
Please suggest us why it shows negative value.

Instance Efficiency Percentages (Target 100%)

Buffer Nowait %: 99.87 Redo NoWait %: 99.99
Buffer Hit %: 92.17 In-memory Sort %: 100.00
Library Hit %: -3,321.23 Soft Parse %: 81.95
Execute to Parse %: 92.88 Latch Hit %: 95.11
Parse CPU to Parse Elapsd %: 87.25 % Non-Parse CPU: 81.39
Re: Negative Values of Library Cache Hit Ratio in AWR Report [message #562133 is a reply to message #562131] Sun, 29 July 2012 05:39 Go to previous messageGo to next message
Michel Cadot
Messages: 59065
Registered: March 2007
Location: Nanterre, France, http://...
Senior Member
Account Moderator
Counter wraps, bug...
Check what is the formula, how the value is computed then check the value in AWR table.

Regards
Michel

[Updated on: Sun, 29 July 2012 05:41]

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Re: Negative Values of Library Cache Hit Ratio in AWR Report [message #562134 is a reply to message #562133] Sun, 29 July 2012 06:26 Go to previous messageGo to next message
mail.madhankumar
Messages: 11
Registered: July 2012
Location: coimbatore
Junior Member
Dear Michel,
Is it bug in AWR Report?. Actualy, We don't have access for production database. it generate report and send mail to us daily. we found that value when we check that report. in our local environment i found one problem like this.. when i check v$rowcache view it's gets value is in negative for dc_users and dc_tablespaces parameter... it may related to production issue which we found in awr report..

Regards,
Madhan
Re: Negative Values of Library Cache Hit Ratio in AWR Report [message #562135 is a reply to message #562134] Sun, 29 July 2012 06:42 Go to previous message
Michel Cadot
Messages: 59065
Registered: March 2007
Location: Nanterre, France, http://...
Senior Member
Account Moderator
Quote:
Is it bug in AWR Report?.


Maybe yes, maybe no, I gave you the way to verify this.

Quote:
when i check v$rowcache view it's gets value is in negative for dc_users and dc_tablespaces parameter...


So seems the counters wrap.
Many Oracle internal counters are still in 32-bit even on 64-bit hardware, OS and Oracle version.
it is not a bug, it is a limit and the workaround is to restart the instance.

Regards
Michel
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