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Step 10 - Diagnosing Performance Problems

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.
Oracle Tutorial - BLOGS

STEP 10 - Next Topics
Monitoring the health of a database and ensuring that it performs optimally is an important task for a database administrator. This discusses the features and functionality included in Oracle Database that make it easy to proactively monitor database health, identify performance problems, and implement any corrective actions. Click on Oracle tuorial links below:
Proactive Database MonitoringDatabase Monitoring
Oracle Diagnosing Performance ProblemsPerformance Problems
Using Advisors to Optimize Database Performance
Oracle Database - PODCASTS
More Tutorials on Oracle dba ...

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Source : Oracle Documentation | Oracle DBA

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