RE: different query performance cluster nodes
- From: "Mark W. Farnham" <mwf@xxxxxxxx>
- To: <greg@xxxxxxxxxxxxxxxxxx>, <eglewis71@xxxxxxxxx>
- Date: Thu, 28 Apr 2011 19:06:24 -0400
First, what Greg said.
Second, I'm a little confused - Is node 1 the "first server"? If you didn't
flip them around it would tend to make me think nearly everything you need
to project the result set is in cache on the "first server" and for some
reason you're sucking wind on cache fusion of those blocks to the "second
server."
If node 1 is the second server, then never mind...
-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx]
On Behalf Of Greg Rahn
Sent: Thursday, April 28, 2011 4:32 PM
To: eglewis71@xxxxxxxxx
Cc: oracle-l@xxxxxxxxxxxxx
Subject: Re: different query performance cluster nodes
System stats only exist for a database, not an instance so that shouldn't be
the issue.
What if you cause a hard parse on both nodes - what plans do you get - the
same ones?
What may be the issue is that stats changed and there was an existing cursor
and it has not been invalidated which could explain different plans on
different nodes. The other thing to check is that there are no differences
in parameters across instances.
On Thu, Apr 28, 2011 at 11:39 AM, Edward Lewis <eglewis71@xxxxxxxxx> wrote:
> We have a 2 node rac cluster.
> When I run a query on node 1, it executes in 1-2 seconds.
> When I run the same query on the node 2, it takes over
> 2 minutes.
> The query plans are different with node 1 using an index, and
> node 2 doing a full table scan.
> The first server has around 583K consistent gets, and
> 6400 physical reads. The second server has 284 consistent gets, and
> 88 physical reads.
> Don't know if this is an issue, but I run system statistics,
> but only on 1 node. I haven't been able to find anything on running
> system stats in a cluster. Is it necessary to run system stats on both
> servers ?
--
Regards,
Greg Rahn
http://structureddata.org
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