Using RDBMS Have You Experienced Enq: Hwm - Contention?

  • From: fmhabash <fmhabash@xxxxxxxxx>
  • To: Oracle L <oracle-l@xxxxxxxxxxxxx>
  • Date: Tue, 05 Apr 2011 15:51:08 -0400

We go hit by this event recently and would like validate the scenario and the proposed solutions against your experience if you encountered it. This event affected a LOB segment in an ASSM tablespaces in a RAC database.

This is what I have found so far ...
1)  As temporary workaround, manually add extra space to the LOB segment.
2) Bug 6376915 (affecting
- >= EVENT="44951 TRACE NAME CONTEXT FOREVER, LEVEL < 1 - 1024 >" - set PCTVERSION to 100: but never able to use blocks freed by updated blobs

3) Bug 6413373 (LOB in RAC and ASSM) - Lob HW enqueue contention: LOBs in ASSM tablespaces
    - Set FREEPOOLS is set to a value >= the number of instances
    - Partition the table into a number of partitions sufficient
4) Try alter system set"_insert_enable_hwm_brokered"=false

If you did encounter this issue, what was you rca and final resolution?

Thank you.

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