RE: Looking for pointers in troubleshooting -> RAC performance degradation (single instance is fine)
Date: Thu, 24 Dec 2009 09:29:32 -0500
There are lot of updates (not inserts) but on some of the tables that are populated by sequences and others without sequences.
I will go through this and see if this helps.
From: Thomas Roach [mailto:troach_at_gmail.com]
Sent: Thursday, December 24, 2009 9:08 AM
To: Pradeep Chetal
Subject: Re: Looking for pointers in troubleshooting -> RAC performance degradation (single instance is fine)
Sorry to early.. meant that it might "NOT" be the right solution for you :)
On Thu, Dec 24, 2009 at 9:07 AM, Thomas Roach <troach_at_gmail.com> wrote:
Are you doing a lot of inserts/updates to tables that have indexes that
are populated by sequences? You should find the objects the contention
is on. To assist with this, take a look at this page.
Basically what "could" be happening (what happened with me) was that I had a bunch of sessions across nodes all fighting to put entries into the same index blocks. Even on one node, this would be a contention issue. What I did to fix my issue was identify the indexes with the contention and made them reverse key indexes. With reverse key indexes you lose the ability to perform certain operations like an index range scan. So if you do queries where something is between this value and that value etc, it might be the right solution for you.
On Thu, Dec 24, 2009 at 8:28 AM, Pradeep Chetal <Pradeep.Chetal_at_mformation.com> wrote:
We have an app that is running well in single instance but when put on a 2-node or 3-node RAC, we see pretty much similar performance. However, if the CPU time is 55-60% in single instance, it becomes 20% in 3-node RAC and top-5 itmed events become..
"gc buffer busy", "gc current block busy", "enq: TX- index contention
Any help in what to look for will be greatly appreciated.
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http://www.freelists.org/webpage/oracle-l Received on Thu Dec 24 2009 - 08:29:32 CST