Viewing Metrics and Thresholds

To effectively diagnose performance problems, statistics must be available. Oracle generates many types of cumulative statistics for the system, sessions, and individual SQL statements. Oracle also tracks cumulative statistics on segments and services. A metric is defined as the rate of change in some cumulative statistic. Metrics are computed and stored in Automatic Workload Repository, and are displayed on the All Metrics page, which can be viewed by clicking All Metrics under Related Links on the Database Home page.

To view metrics for your database:

1. On the Database Home page under Related Links, click All Metrics.

   The All Metrics page appears.

2. Click a specific metric link.

   A details page appears, with more information about the metric. Online Help for this page describes the metric.

Description of the illustration metrics_11gr2.gif

For each of these metrics, you are able to define warning and critical threshold values, and whenever the threshold is exceeded, Oracle Database issues an alert. Alerts are displayed on the Database Home page under the Alerts heading (or Related Alerts for nondatabase alerts such as a component of Oracle Net).

The following figure shows two warning alerts for the threshold Tablespace Space Used.

Setting thresholds is discussed in "Setting Metric Thresholds". Actions you might take to respond to alerts are discussed in "About Responding to Alerts".

When the condition that triggered the alert is resolved and the metric value is no longer outside the boundary, Oracle Database clears the alert. Metrics are important for measuring the health of the database and serve as input for self-tuning and recommendations made by Oracle Database advisors.