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: Mon, 16 Jan 2012 16:33:35 -0600

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)

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: Monday, January 16, 2012 4:28 PM
To: Taylor, Chris David
Cc: 'oracle-l@xxxxxxxxxxxxx'
Subject: Re: SQL Performance Problem between 2 Databases WITH FIX included for 
this case

A 10053 trace won't do you any good if the plans are the same. But you don't 
necessarily need a 10046 trace either. Just looking at v$session_event will 
give you that info as well. I've taken a page out of Tom Kyte's runstats script 
and created bstat / estat sql scripts. bstat save the current values to a GTT. 
Estat does the same and the prints the deltas.
Or you could use Tanel's snapper script. Although that could present a problem 
for the faster query. 

Regards
Wolfgang Breitling
Centrex Consulting Corporation
http://www.centrexcc.com

On 2012-01-16, at 3:04 PM, Taylor, Chris David wrote:

> 
> D1:
> Elapsed times include waiting on following events:
>  Event waited on                             Times   Max. Wait  Total Waited
>  ----------------------------------------   Waited  ----------  ------------
>  SQL*Net message to client                       1        0.00          0.00
>  direct path write temp                       1016        0.09          0.44
>  latch free                                      1        0.00          0.00
>  direct path read temp                        4572        0.03          3.79 
> <------------------ LOOK
>  db file sequential read                       238        0.01          0.55
>  db file scattered read                        229        0.01          0.50
>  SQL*Net message from client                     1        4.74          4.74
> *******************************************************************************
> 
> D2:
> Elapsed times include waiting on following events:
>  Event waited on                             Times   Max. Wait  Total Waited
>  ----------------------------------------   Waited  ----------  ------------
>  SQL*Net message to client                       1        0.00          0.00
>  direct path write temp                       1030        0.08          0.18
>  db file sequential read                         2        0.00          0.00
>  local write wait                              171        0.01          0.25
>  direct path read temp                       66950        0.19         39.85  
> <-----------------------LOOK
>  SQL*Net message from client                     1       32.32         32.32
> *******************************************************************************
> 
> I'm such a dumb*** sometimes.
> 
> I was out of (or low in) PGA memory in D2 due to the heavy usage by the 
> development staff.
> 
> Bump up PGA_AGGREGATE_TARGET and performance goes back to sub 3 secs for the 
> query.  Now D1 and D2 perform exact.
> 
> This is WHY a 10046 trace should be FIRST step in examining a performance 
> issue so you can *know* what you are waiting on before even thinking about 
> 10053 traces. (In my honest opinion anyway).
> 



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