RE: Event 10046 and Performance

[Cary Millsap]

Title: Event 10046 and Performance

Ah, the “secret power” of event 10046 reaches the light of day at last!   J Just kidding… Is there a chance that it’s coincidence, that some workload variation that causes poor performance just happens not to have occurred since you instrumented the form?   My advice is to be patient and leave the instrumentation there until the problem manifests itself again. Then you’ll have everything you need to fully diagnose the issue in the session’s trace file.   Cary Millsap Hotsos Enterprises, Ltd. http://www.hotsos.com Upcoming events: - Hotsos Clinic, Dec 9–11 Honolulu - 2003 Hotsos Symposium on Oracle® System Performance, Feb 9–12 Dallas - Jonathan Lewis' Optimising Oracle, Nov 19–21 Dallas -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Jamadagni, Rajendra Sent: Friday, November 15, 2002 4:49 PM To: Multiple recipients of list ORACLE-L Subject: Event 10046 and Performance   Okay ... here is a curved ball ... This AM an application support person called and mentioned that we have a form that has become slow compared to 2 days ago. So we saw the slow behavior and then I did a 10046 trace on it. After analysis, found that one query is taking about 90% of total time and isolated it to be worked on. On our day-old instance (refreshed daily from prod), this form runs very fast. After comparing everything, I found that for some test we have db_file_multiblock_read_count = 4 whereas it is 32 (don't ask) on production. So after changing this variable in my session to 4 (on production), I checked the explain plan and it seems to be okay, picking up the right indexes etc. So, I asked the support person to add following line in pre-form trigger on the form and run a test forms_ddl('alter session set db_file_multiblock_read_count=4'); ran the form, no change in the performance. So I requested following like to be addes as well forms_ddl('alter session set events ''10046 trace name context forever, level 8'''); The form runs as fast as it can. So we thought maybe flushing the shared pool might help, so we flushed the shared pool (again don't ask, this is prod env, lunch time, light load). Still same, with 10046 event set, the form runs as fast as it can, but if I take it out, it slows down. I am confused ... does anyone have a plausible explanation on why this is happening? Oracle 9201, AIX 5l Raj ______________________________________________________ Rajendra Jamadagni              MIS, ESPN Inc. Rajendra dot Jamadagni at ESPN dot com Any opinion expressed here is personal and doesn't reflect that of ESPN Inc. QOTD: Any clod can have facts, but having an opinion is an art!