To make matters even worse, because historically the database was the problem, end users are trained to expect it's an "Oracle problem," putting anyone remotely connected with Oracle on the defensive. It is not unusual for the DBA to reconstruct the end-to-end response time profile before the group who can make a real performance difference will get involved.

Another tricky and rarely discussed reality is that through both tracing Oracle processes or using Oracle's performance views, it is impossible to determine end-to-end response time. Let me say that again-impossible. Don't be fooled by fancy vendors or the promises of tracing and session profiling. Tracing and Oracle's performance views reach from the database server out to as far as the Oracle client process, and then stop. Beyond the Oracle client process, DBAs must use other tools to understand the remaining user experience time.

But it gets even more depressing. By looking at all sessions-that is, at a system-level response-time analysis perspective, the best the performance views can do is tell us about the timing related to the server process. We lose the ability to ascertain the time between the Oracle server process and its associated client process(es).