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Step 10 - Diagnosing Performance Problems
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Learn Oracle - Viewing Performance Analysis
ADDM runs automatically every 30 minutes to coincide with the snapshots taken by
AWR. Its output consists of a description of each problem it has identified, and a
recommended action.
Findings are displayed in two places on the home page:
Under the Performance Analysis section on the Database Home page
Oracle DBA can drill down by clicking the finding. The Findings Details page appears
describing the findings and recommended actions.
Below the Diagnostic Summary heading next to Performance Findings shows the
number of findings if any. Clicking this link takes Oracle DBA to the ADDM page
Responding to Performance Findings
To respond to a performance finding, click the finding and follow the recommended
actions, if any. A recommendation can include running an advisor.
Clicking this link takes Oracle DBA to the Performance Finding Details page. Here the
recommended action is to run the SQL Advisor, which Oracle DBA can do by clicking Run
Advisor Now. The advisor runs and gives a recommendation in the form of precise
actions for tuning the SQL statements for better performance.
Modifying Default ADDM Behavior
ADDM behavior and analysis is based on the AutomaticWorkload Repository (AWR),
which collects system performance statistics and stores the data in the database. After
default installation, the AWR captures data every hour and purges data over seven
days old. Oracle DBA can modify both the snapshot frequency and the data retention period
as desired.
Oracle DBA can view and alter these settings on the Workload Repository page:
The retention period for snapshots. This is initially set to 7 days.
The interval for snapshots. The default and recommended value is 30 minutes.
To navigate to this page, from the Database Administration page, under Workload,
select Automatic Workload Repository.
To change either of these settings, click Edit on the Workload Repository page. The
Edit Settings page appears. Enter a new Snapshot retention period or new System
Snapshot Interval. Click OK.
Running ADDM Manually
By default Oracle runs ADDM every hour. Performance findings from the last
snapshot are listed on the Oracle Enterprise Manager Home page. Oracle DBA can also invoke ADDM manually. Reasons for doing so include running it as a
recommended action associated with an alert, running it in the middle of a snapshot
period, or running it across multiple snapshots.
From the Home page, under Related links Oracle DBA can navigate to the ADDM page by
clicking Advisor Central, then ADDM. The Create ADDM Task page appears.
To analyze a period across
multiple snapshots, select a start time and click OK, then choose and end time and
click OK. The ADDM Task page appears detailing any findings.
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