Monthly Archives: June 2008

Another use case for WaitProf – diagnosing “events in waitclass Other”

I recently diagnosed a performance issue where the “events in waitclass Other” occasionally took significant part of the session’s response time. For example Snapper (which reads wait event data from V$SESSION_EVENT) reported that during measuring 39.9% of the response time … Continue reading

Posted in Oracle | Tagged , , , | 7 Comments

Advanced Oracle Troubleshooting Guide, Part 6: Understanding Oracle execution plans with os_explain

Get ready for some more adventures in Oracle process stack! Before proceeding though, please read this post about safety of different stack sampling approaches. I have had few non-trivial Oracle troubleshooting cases, related to query hangs and bad performance, where … Continue reading

Posted in Cool stuff, Oracle | Tagged , , , , , | 24 Comments

Advanced Oracle Troubleshooting Guide, Part 5: Sampling V$ stuff with WaitProf. Really fast. Using SQL!

I bet you thought I’ll be writing about direct SGA access?! ;) Nope! Direct SGA access has excellent troubleshooting potential (as long as you know the shared memory data structures), but it has one major drawback – very few companies … Continue reading

Posted in Cool stuff, Oracle | Tagged , , , , | 27 Comments