Oracle have provided many performance gathering and reporting tools over the years. In earlier releases, UTLBSTAT/UTLESTAT scripts were used to monitor performance metrics. Oracle8i introduced the Statspack functionality which Oracle9i extended. In Oracle 10g statspack has evolved into the Automatic Workload Repository (AWR).

Automated Workload Repository (AWR) report, which is very similar to the STATSPACK elapsed-time report.  The AWR elapsed-time report contains valuable information regarding the health of the Oracle instance, but considerable skill is required to fully understand and interpret each section.

This is very helpful report in analyzing the database health and diagnostics.

AWR Features

The AWR is used to collect performance statistics including:

• Wait events used to identify performance problems.
• Time model statistics indicating the amount of DB time associated with a process from the V$SESS_TIME_MODEL and V$SYS_TIME_MODEL views.
• Active Session History (ASH) statistics from the V$ACTIVE_SESSION_HISTORY view.
• Some system and session statistics from the V$SYSSTAT and V$SESSTAT views.
• Object usage statistics.
• Resource intensive SQL statements.

The repository is a source of information for several other Oracle database features including:

• Automatic Database Diagnostic Monitor
• SQL Tuning Advisor
• Undo Advisor
• Segment Advisor

Workload Repository Views

The following workload repository views are available:

• V$ACTIVE_SESSION_HISTORY - Displays the active session history (ASH) sampled every second.
• V$METRIC - Displays metric information.
• V$METRICNAME - Displays the metrics associated with each metric group.
• V$METRIC_HISTORY - Displays historical metrics.
• V$METRICGROUP - Displays all metrics groups.
• DBA_HIST_ACTIVE_SESS_HISTORY - Displays the history contents of the active session history.
• DBA_HIST_BASELINE - Displays baseline information.
• DBA_HIST_DATABASE_INSTANCE - Displays database environment information.
• DBA_HIST_SNAPSHOT - Displays snapshot information.
• DBA_HIST_SQL_PLAN - Displays SQL execution plans.
• DBA_HIST_WR_CONTROL - Displays AWR settings.

Note: The AWR is licensed as part of the diagnostic pack. Be sure you are licensed before you use this in production.