Wednesday, August 24, 2011

Difference between Statspack and AWR..

1.) STATSPACK does not store the Active Session History (ASH) statistics which are available in the AWR dba_hist_active_sess_history view.

2.)An important difference between STATSPACK and the AWR is that STATSPACK does not store history for new metric statistics introduced in Oracle10g. The key AWR views, dba_hist_sysmetric_history and dba_hist_sysmetric_summary.

3.)Statspack snapshots must be run by an external scheduler (dbms_jobs, CRON, etc.). AWR snapshots are scheduled every 60 minutes by default. Administrators can manually adjust the snapshot interval if so desired.

4.)ADDM captures a much greater depth and breadth of statistics than Statspack does. 

5.)Statspack snapshot purges must be scheduled manually.AWR snapshots are purged automatically by MMON every night. MMON, by default, tries to keep one week's worth of AWR snapshots available. If AWR detects that the SYSAUX tablespace is in danger of running out of space, it will free space in SYSAUX by automatically deleting the oldest set of snapshots.