Re: Oracle RAC TEMP / TEMP GROUP tablespace performance question

  • From: "Jonathan Lewis" <jonathan@xxxxxxxxxxxxxxxxxx>
  • To: <oracle-l@xxxxxxxxxxxxx>
  • Date: Tue, 19 Feb 2013 17:35:11 -0000

ITL waits on indexes on GTTs shouldn't be possible. GTTs are private to 
sessions, ITL waits on indexes should require multiple sessions modifying 
the same block.

Bear in mind that you are using 10.2.0.4, and Riyaz' note is about 11.2.and 
mentions changes made to deal with RAC-specific options  - any advice you 
get may not be appropriate for your version, and some of the anomalies you 
see may only be relevant to your version.

I note that you've got temporary LOBs hitting the system - what do your 
Instance Activity stats look like (in a typical snapshot) for physical read 
and write to temp, and does your version further split these down to show 
temp LOBs separately ? Also, if you ran Riyaz' query for cached and used 
extents, what does it look like ?


Regards

Jonathan Lewis
http://jonathanlewis.wordpress.com/all-postings

Author: Oracle Core (Apress 2011)
http://www.apress.com/9781430239543

----- Original Message ----- 
From: <Christopher.Taylor2@xxxxxxxxxxxx>
To: <kellyn.potvin@xxxxxxxxx>; <gajav@xxxxxxxxx>; <mwf@xxxxxxxx>
Cc: <oracle-l@xxxxxxxxxxxxx>
Sent: Tuesday, February 19, 2013 4:50 PM
Subject: RE: Oracle RAC TEMP / TEMP GROUP tablespace performance question


| Yes have AWR data.  Any Temp wait events are really low on the list.
|
| I do have ITL waits on the global temp indexes though due to the way we 
run sessions concurrently for different facilities.  (Think roughly 20 
sessions per node, processing different facilities - doing calculations 
etc, but hitting the same underlying objects for each session.  Some 
objects are partitioned which helps, but the GTemp tables experience 
concurrency waits)
|
| Chris
|
| -----Original Message-----
| From: oracle-l-bounce@xxxxxxxxxxxxx 
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of Kellyn Pot'vin
| Sent: Tuesday, February 19, 2013 10:45 AM
| To: Taylor Christopher - Nashville; gajav@xxxxxxxxx; mwf@xxxxxxxx
| Cc: oracle-l@xxxxxxxxxxxxx
| Subject: Re: Oracle RAC TEMP / TEMP GROUP tablespace performance question
|
| Do you have AWR data available to you? Can you see if you have temp waits 
for read and writes? Are the GTT's performance strains for any of these 
processes that come up in your "top 10" offending processes?
|
|

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