RE: SQL Performance Problem between 2 Databases WITH FIX included for this case
- From: "Taylor, Chris David" <ChrisDavid.Taylor@xxxxxxxxxxxxxxx>
- To: 'Wolfgang Breitling' <breitliw@xxxxxxxxxxxxx>
- Date: Tue, 17 Jan 2012 11:06:45 -0600
Some of that is subjective isn't it? (I'm asking)
For me enabling a 10046 trace is not clumsy at all and if the sql is executing
I can enable it and get at least a partial 10046, and since SQL is capturable I
can grab it and execute in a test session.
For me, digging through V$ tables is clumsy precisely because I'm not as
familiar with them - I will concede I should probably make that part of my
toolbox where I am comfortable banging away at V$ information for a particular
query that is in process.
Typically I imagine this scenario:
1. Bad performing SQL -> 2. Examine V$ views -> 3.Determine some cause of
performance issue -> 4.Implement Some fix -> 5. See if query responds on next
run (since current run won't be affected) 6. -> *IF* query not affected as
expected, then you're probably going to go to the 10046 trace level?
It seems like there is a good chance (and perhaps I overestimate the chance)
that we are both going to end up looking at a 10046 trace for any problem that
is significant. (Oracle EM can usually take care of the non-significant ones
through SQL Tuning advisors)
Most often in a transaction or job (a connected session) there are only 1 or 2
offending SQLs. A 10046 where you're looking at gobs of SQL statements is not
very helpful in my opinion. Target the offending SQL(s) only.
Chris Taylor
Sr. Oracle DBA
Ingram Barge Company
Nashville, TN 37205
"Quality is never an accident; it is always the result of intelligent effort."
-- John Ruskin (English Writer 1819-1900)
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-----Original Message-----
From: Wolfgang Breitling [mailto:breitliw@xxxxxxxxxxxxx]
Sent: Tuesday, January 17, 2012 9:52 AM
To: Taylor, Chris David
Cc: 'oracle-l@xxxxxxxxxxxxx'
Subject: Re: SQL Performance Problem between 2 Databases WITH FIX included for
this case
But that requires that you start a trace ( with level 12 ) prior to executing
the sql. The row counts and timing you can get from v$sql_plan and
v$sql_plan_statistics and the wait events from v$session_event. I am not
disputing the usefulness of a 10046 trace. I was merely replying to you comment
about the 10053 trace. You need to use the appropriate tools for the task at
hand and there are different ways to attack a problem. To analyze the
performance of a single sql a 10046 trace would not be my first choice. Far too
clumsy. The mentioned v$ views ( plus maybe a few more ) are sufficient for
that. To analyze the performance of an entire transaction or job, of course I'd
request a 10046 trace because nothing else gives you the full picture.
Regards
Wolfgang Breitling
Centrex Consulting Corporation
http://www.centrexcc.com
On 2012-01-16, at 3:33 PM, Taylor, Chris David wrote:
> I'm still partial to the 10046 due to all the information it gives you. Does
> Tom's bstat/estat script give execution plans with row counts and wait events
> and recursive sqls? If not, I can get all that at once :)
>
> (But I still have to remember to actually look at all of it and not get too
> single minded about a particular piece of it)
>
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