Re: different query performance cluster nodes

From: ed lewis <>
Date: Thu, 28 Apr 2011 20:35:13 -0400
Message-ID: <35F5E2BDC36B428D92D4BC2B8AC4ACA3_at_CATHY>


    Yes, Node 1 is the first server.

    And, yes it would appear that the
node 1 has what's required for the result set.

  • Original Message ----- From: "Mark W. Farnham" <> To: <>; <> Cc: <> Sent: Thursday, April 28, 2011 7:06 PM Subject: RE: different query performance cluster nodes

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: [] On Behalf Of Greg Rahn
Sent: Thursday, April 28, 2011 4:32 PM
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 <> 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 ?

Greg Rahn

Received on Thu Apr 28 2011 - 19:35:13 CDT

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