Oracle AWR baseline

Internally, an AWR baselines is a range of snapshots that can be used to compare to other pairs of snapshots. The Oracle database server will exempt the snapshots assigned to a specific baseline from the automated purge routine. Thus, the main purpose of a baseline is to preserve typical runtime statistics in the AWR repository, allowing you to run the AWR snapshot reports on the preserved baseline snapshots at any time and compare them to recent snapshots contained in the AWR.

This allows you to compare current performance (and configuration) to established baseline performance, which can assist in determining database performance problems.

 How to create/drop AWR baseline?

To create a baseline of performance of the system, one create a baseline and used for later comparisons. If a snapshot id passed in is invalid the procedure will return an error message indicating it is invalid. The snapshot baseline will be kept till it is dropped manually.

SQL> EXEC dbms_workload_repository.create_baseline(start_snap_id=>1, end_snap_id=>10, baseline_name=>'First baseline');

-- If cascade is TRUE, it will also drop the snapshot in the baseline.
-- If cascade is FALSE, it will only drop the baseline (not the snapshot)
SQL> EXEC dbms_workload_repository.drop_baseline(baseline_name=>'First baseline', cascade=>false);

-- view baseline name, start and end snap id
SQL> select BASELINE_NAME, START_SNAP_ID, END_SNAP_ID from dba_hist_baseline;