AWR

AWR (Automatic Workload Repository) is a built-in Oracle Database component that automatically collects system performance statistics at regular intervals (every 60 minutes by default) and retains them for a configurable period.

How it works #

AWR captures periodic snapshots that include:

• Session statistics and wait events
• SQL metrics (top SQL by execution time, I/O, CPU)
• Memory structure statistics (SGA, PGA)
• I/O statistics by datafile and tablespace

What it’s for #

The AWR report is the primary tool for diagnosing performance issues in Oracle. By comparing two snapshots you can identify:

• Queries consuming excessive resources
• Changes in execution plans
• I/O, CPU or memory bottlenecks
• Performance regressions after application deployments

When to use it #

AWR is the first tool to consult when you receive a slowness report. Together with ASH (Active Session History), it lets you reconstruct what happened in the database during a specific time window, even after the problem has resolved.