>i am currently investigating which session consume the most cpu-time per instance. just count ON-CPU records from DBA_HIST_ASH... It's an aproximation but quite good. My understanding is that OEM just do the same thing, at least this is what I saw in OEM queries. p.s. CPUtime could be TotalTime minus WaitTime. I suppose in reality (truss reality for example) it isn't but well, this is what Oracle thinks :) --------------------------------------------------------------------------------- Please consider the environment before printing this e-mail From: Jan-Hendrik Boll <jan.hendrik.boll@xxxxxxxxxxxxxx> To: oracle-l@xxxxxxxxxxxxx Date: 2011.10.11 12:33 Subject: Finding out historical cpu-usage Hi Lister's, i am currently investigating which session consume the most cpu-time per instance. In order to do so i am using the view dba_hist_active_sess_history Tracking down the time spent waiting for typical wait-events like 'log file sync' seems easy as it is the sum of time_wait for that event. But how can i find out the CPU-Time? Is CPU time the sum of wait_time in which the session_state equals 'ON CPU' ? Any clarification about the meaning of these two columns would be greatly appreciated. Kind regards, Jan-Hendrik Boll -- //www.freelists.org/webpage/oracle-l -- //www.freelists.org/webpage/oracle-l