Re: RAC PARALLEL
- From: Sanjay Mishra <smishra_97@xxxxxxxxx>
- To: Andrew Kerber <andrew.kerber@xxxxxxxxx>, "mwf@xxxxxxxx" <mwf@xxxxxxxx>
- Date: Thu, 13 Oct 2011 06:09:11 -0700 (PDT)
Thanks Andrew. I was not aware of this and found late that 11g R2 has got the
following new parameters.
1,PARALLEL_DEGREE_POLICY:
2,PARALLEL_MIN_TIME_THRESHOLD:
3,PARALLEL_DEGREE_LIMIT:
4,PARALLEL_FORCE_LOCAL:
This is what I found yesterday when I mentioned in the last update that Old
Instrance_groups and PARALLEL,.. are deprecated in 11g R2 and even still there
for backward compatability. This is what I was trying to set today to restrict
the Parallel to Local Node.
Regards
Sanjay
________________________________
From: Andrew Kerber <andrew.kerber@xxxxxxxxx>
To: mwf@xxxxxxxx
Cc: tim@xxxxxxxxx; Sanjay Mishra <smishra_97@xxxxxxxxx>; oracle-l@xxxxxxxxxxxxx
Sent: Thursday, October 13, 2011 8:41 AM
Subject: Re: RAC PARALLEL
I'm surprised no one mentioned this. If this is 11g there is a
parameter called parallel_force_local. Make sure this is set to true.
If not, you can end up running parallel operations on remote nodes,
which will both adversely affect operations on other nodes, but will
also cause massive gc waits when data is returned unless you have a very high
speed interconnect (ie, at least 10 gigabit). On 10g this is done by setting
the parallel groups and such, I would have to look it up to
find the exact details.
As others have mentioned, it is unlikely that parallel is a good
idea on OLTP, but but some of the other parameters you need to look at
are parallel_min_servers, parallel_max_servers. I have found that
setting the parallel_min_servers saves a lot of time in the startup of
parallel queries and parallel_max_servers will help keep the load down
at high usage times.
(note: resent because I overquoted a few minutes ago).
--
Andrew W. Kerber
'If at first you dont succeed, dont take up skydiving.'
--
//www.freelists.org/webpage/oracle-l
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