Re: Instance Efficiency Percentages - Library Hit %: in AWR
Date: Wed, 4 Apr 2012 13:56:11 -0700 (PDT)
Although I can't help you directly on the SQL you requested, but once you do start trend this phenomenon, here are a few things that will provide food for investigation and thought:
- What the are Top 5 Wait Events when this Instance Efficiency Percentage is low?
- Which SQL statements are being negatively affected by the Top 5 Wait Events? By how much?
- Is there a problem on your database for the period of the snapshot(s)?
- How does this snapshot's workload compare to a baseline snapshot?
- Is there evidence of some sort of abnormal application workload?
- Did you have more parsing than normal?
- What caused the increased parsing (if applicable)?
- Or was the increased parsing due to automatic memory management stealing from the shared pool to feed the db buffer cache in response to an increase I/O load?
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From: Sreejith S Nair <Sreejith.Sreekantan_at_ibsplc.com> To: oracle-l_at_freelists.org
Sent: Wednesday, April 4, 2012 2:39 AM
Subject: Instance Efficiency Percentages - Library Hit %: in AWR
In AWR under Instance Efficiency Percentages we see a Library Hit % and we find it very low for one snapshot. I would like to know the trend for few more days available in AWR snapshots
(dba_hist_snapshot,DBA_HIST_LIBRARYCACHE) using SQL Query.
Can some one please help with how this % is being calculated. What SQL can I use to calculate this ? May be for a range of snapshot. Thanks in Advance.
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Sreejith S Nair
Associate Systems Architect | AOS DBA Team IBS Software Services Private Ltd.
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http://www.freelists.org/webpage/oracle-l Received on Wed Apr 04 2012 - 15:56:11 CDT