Re: RAC is slower than non-RAC for batch job with lots of update/delete?

  • From: Paul Albeck <palbeck_ar@xxxxxxxxxxxx>
  • To: staywithpin@xxxxxxxxx, oracle-l <oracle-l@xxxxxxxxxxxxx>
  • Date: Thu, 18 Oct 2007 07:18:29 -0700 (PDT)

Hi,
It's common to see some performance impact in these cases.  The most common 
problem I've seen is Oracle having to do consistent reads on the blocks it's 
reading, therefore having to reads rollbacks segments, sometimes on the other 
node.
If you trace your session with RAC and without RAC you'll probably see much 
more gets in the RAC trace.  One way to minimize this impact is to commit more 
often (against common wisdom..)
Regards, Paul

----- Original Message ----
From: qihua wu <staywithpin@xxxxxxxxx>
To: oracle-l <oracle-l@xxxxxxxxxxxxx>
Sent: Thursday, October 18, 2007 7:03:01 AM
Subject: RAC is slower than non-RAC for batch job with lots of update/delete?


Hi, everyone,

After our database changed into RAC enviroment, the batch job is very slow. I 
am wondering whether RAC is not good for batch job. As batch job only use one 
session and only connect to one instance, but when update/delete data, sometime 
"gc current request" wait occurs as the block must be read from the other node. 
Without RAC, then this kind of wait will gone, so I think RAC is not good for 
batch job with plenty of update/delete operations. Anyone doesn't agree?


Thanks,
Qihua






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