Oracle Tips

From Server run $ORACLE_HOME/rdbms/admin/awrddrpt.sql

From SQLPLUS:
select snap_id, end_interval_time
from dba_hist_snapshot
where end_interval_time > trunc(sysdate-1)
order by snap_id;

8945                                   28/07/2009 12:00:18.555 AM      
8946                                   28/07/2009 1:00:30.647 AM        
8947                                   28/07/2009 2:00:42.740 AM        
8948                                   28/07/2009 3:00:55.045 AM        
8949                                   28/07/2009 4:00:07.050 AM        
8950                                   28/07/2009 5:00:19.198 AM        

Now that I have those snapshot ids, I can generate the AWR differences report, passing in the DBID, Instance Number, Begin and End Snapshot IDs for the first period and then the second period.

select * from TABLE (
DBMS_WORKLOAD_REPOSITORY.awr_diff_report_html(4034329550,1,8947,8951,4034329550,1,8971,8975 ));