If wait_time is greater than zero, the session currently has a session_state of ON CPU, and the EVENT listed is the event that was last waited for before this sample. Oracle 10g introduced ASH and Oracle 11 builds upon that foundation. My doubt is session 2 will be running till session 1 gets committed, so how much time will session 2 wait for session 1, is there any pre-defined timeout time defined for the same, say for example even after 20 mins, the session 2 is still trying to update waiting for session 1 to be completed, so when session 2 will be aborted/timed out. The changes that are being made should last under a few hundredths of a second, e.g. time_waited will only contain a value when waits are occurring at the instant the sample is taken. With Oracle Database 10g, many previously difficult-to-attain response-time metrics are now at your fingertips.

Historically, in trying to achieve maximum database performance, Oracle DBAs and performance analysts have fought an uphill battle to obtain solid response time metrics for … If the session is not in a wait, then the value is the amount of time since the start of the last wait .

WAIT_TIME – micro, not for general use TIME_WAITED – micro, only the last sample is fixed up, the others will have TIME_WAITED=0* dba_hist_active_sess_history One of those SQL statements, slightly reformatted, appears below: SELECT A.CURRENT_OBJ#, O.OBJECT_NAME, O.OBJECT_TYPE, A.EVENT, SUM(A.WAIT_TIME +…

3/ You cannot in general hope to add up TIME_WAITED over samples and get “total wait time” for session 4/ Enqueue waits like your experiment time-out every 3 seconds and re-wait. Another session holds the buffer in an incompatible mode to our request While the block is being changed, the block is marked as unreadable by others. June 28, 2011 While reading the alpha edition of the “Oracle Database 11g Performance Tuning Recipes” book, I noticed a couple of interesting SQL statements in Recipe 5-17 that just did not look right. ASH is a radically new way to gather performance data. Thanks for the question, Anil. Is ready to be run on Unix or Linux Usage: chkwait review the variables section to customize it for your environment. -- TOP events select event, sum(wait_time +time_waited) ttl_wait_time from v$active_session_history where sample_time between sysdate - 60/2880 and sysdate

a disk read should be under 20 milliseconds and a block modification should be under one millisecond. Answered by: Tom Kyte - Last updated: May 07, 2012 - 10:29 am UTC The time_waited will be zero. Asked: August 15, 2001 - 10:02 pm UTC. Oracle DBA scripts: Active Session History Queries -- TOP events select event, sum(wait_time +time_waited) ttl_wait_time from v$active_session_history Session was captured into ASH waiting for enqueue in 8 samples.