Insert contention on RAC

From: Baumgartel, Paul <>
Date: Wed, 25 Jun 2008 15:18:39 -0400
Message-ID: <>

To borrow the style from some MetaLink notes--

Fact:  Oracle
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?


Paul Baumgartel
Information Technology
Prime Services Databases Americas
One Madison Avenue
New York, NY 10010
Phone 212.538.1143

Please access the attached hyperlink for an important electronic communications disclaimer:

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

Original text of this message