Automatic Database Diagnostic Monitor

Automatic Database Diagnostic Monitor
Oracle Database includes a self-diagnostic engine called Automatic Database
Diagnostic Monitor (ADDM). ADDM makes it possible for Oracle Database to
diagnose its own performance and determine how identified problems can be
resolved.
To facilitate automatic performance diagnosis using ADDM, Oracle Database
periodically collects snapshots of the database state and workload. Snapshots are sets
of historical data for specific time periods that are used for performance comparisons
by ADDM. Snapshots provide a statistical summary of the state of the system at a
point in time. These snapshots are stored in Automatic Workload Repository (AWR),
residing in the SYSAUX tablespace. The snapshots are stored in this repository for a set
time (8 days by default) before they are purged to make room for new snapshots.
ADDM analyzes data to determine the major problems in the system, and may
recommend solutions and quantify expected benefits. ADDM analysis results are
represented as a set of findings.
EM Express provides three types of ADDM findings.
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