Insert contention on RAC

From: Baumgartel, Paul <paul.baumgartel_at_credit-suisse.com>
Date: Wed, 25 Jun 2008 15:18:39 -0400
Message-ID: <21469B88E0EA11498818517F210335310455B08A@EPRI17P32001A.csfb.cs-group.com>

To borrow the style from some MetaLink notes--

Fact:  Oracle 10.2.0.1.0
Fact:  RedHat 3
Fact:  3 node RAC

Many concurrent sessions inserting one row at a time into the same table. On first run, table in ASSM tablespace, about 50% of database service time was gc buffer busy waits. Built a new tablespace with manual segment management, re-created table with three freelist groups and 4 freelists. Next run showed >90% of service time was enq: HW contention; total run time was slightly higher than it was with ASSM.. Re-created table again, allocated three 4 GB extents, one for each instance. Current run is still showing high HW contention waits.

Might I have too many freelists? Other than forcing all sessions to use the same RAC instance, is there anything else I can do to reduce these waits?

Thanks,

Paul Baumgartel
CREDIT SUISSE
Information Technology
Prime Services Databases Americas
One Madison Avenue
New York, NY 10010
USA
Phone 212.538.1143
paul.baumgartel_at_credit-suisse.com
www.credit-suisse.com

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Received on Wed Jun 25 2008 - 14:18:39 CDT