Well it was unknown to me until yesterday and possibly this is new thing for no one but me, but lets blog it anyway :)
One of the most nice thing about the newer versions of Oracle is the advent of ASH and AWR as they provide awesome diagnostic information. Many customers at the Pythian use Real Application Cluster and having a cluster wide AWR report by using awrgrpt.sql script is very handy.
But often we need to zero-in to certain spikes and blips which occur within very short span of time and due to the interval of AWR report it becomes nearly impossible to go back in history and pinpoint the issue to that very minute time slot using AWR report.
Cluster wide ASH report comes to the rescue. The script ashrpti.sql lets you specify ALL or instances by number like 1,2,3,4 during its run to get the cluster wide report. You can specify the time duration and many other things like SQL_ID to pull out the specific report you want.
Both awrgrpt.sql and ashrpti.sql reside in $ORACLE_HOME/rdbms/admin directory.