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RE: Execution Plans in trace files??

From: Cary Millsap <cary.millsap_at_hotsos.com>
Date: Tue, 19 Nov 2002 15:38:59 -0800
Message-ID: <F001.00507656.20021119153859@fatcity.com>


Robert,

The Oracle kernel emits STAT lines into the trace data stream only upon cursor close. It's somewhat inconvenient. I wish the STAT lines were emitted when the execution plan is constructed, but alas, they're not. This note might encourage some folks on the list to ask for that as an enhancement.

That behavior is not new to 9.2; it's always been that way. Are you by chance explicitly deactivating SQL trace before your cursors close? An easy way to ensure that all your STAT lines are in your trace data is to simply leave SQL trace activated until the session exits.

So, isn't this exciting? :) There are already about 70 pages (and counting) of stuff in the new book project *just*about*SQL*trace*data.

P.S.: I'm glad that you're looking at raw trace data, because TKPROF is an awful liar about execution plans among other things. You can see it if you know how to put together the raw STAT lines. It's one of the many reasons motivating our construction of www.hotsos.com/products/profiler.

Cary Millsap
Hotsos Enterprises, Ltd.
http://www.hotsos.com

Upcoming events:

- Hotsos Clinic, Dec 9-11 Honolulu
- 2003 Hotsos Symposium on OracleŽ System Performance, Feb 9-12 Dallas
- Jonathan Lewis' Optimising Oracle, Nov 19-21 Dallas


-----Original Message-----
Robert
Sent: Tuesday, November 19, 2002 4:49 PM To: Multiple recipients of list ORACLE-L

Sorry for the double post all, someday I'll learn to get my subject lines
right!!

I've got 9.2 loaded up on my laptop, have for some time. I've been playing
around with base trace files (haven't done that in a while) and discovered
something interesting. I found within the trace file the actual execution
plan for the SQL statement being run. Now, I don't mean the TKPROF output
here, rather I'm talking about the trace file generated by the database session itself.

I looked on my AIX Oracle 9.2 databases and I'm not seeing this behavior
here. I've done some looking around but find nothing on this. Is there some
parameter that is set to enable the inclusion of the execution plan in trace
files? I've never noticed this behavior before, is this new, or something
specific to the NT port?

RF

Robert G. Freeman - Oracle OCP
Oracle Database Architect
CSX Midtier Database Administration
Author of several Oracle books you can find on Amazon.com!

Londo Mollari: Ah, arrogance and stupidity all in the same package. How efficient of you.
 
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Author: Freeman, Robert
  INET: Robert_Freeman_at_csx.com

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Author: Cary Millsap
  INET: cary.millsap_at_hotsos.com

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