on 11-14-2013 3:13 PM
Hi all,
We have done the following database parameter changes
SQL> show parameter _securefiles_concurrency_estimate
NAME TYPE VALUE
------------------------------------ -----------
------------------------------
_securefiles_concurrency_estimate integer 50
SQL> show parameter _simple_view_merging
NAME TYPE VALUE
------------------------------------ -----------
------------------------------
_simple_view_merging boolean FALSE
We have also applied latest SBP after that changes Entire performance has
been downgraded.
Please suggest.
Regards,
MS
hi MS,
Please have a look at this SAP Note.
Note 1431798 - Oracle 11.2.0: Database Parameter Settings
Regards,
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Hi,
What is the Oracle release and version?
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Hello
Parameter _securefiles_concurrency_estimate should improve performance for update access on securefiles (aka Lob)
Securefiles DMLs cause high 'buffer busy waits' & 'enq: TX - contention' wait events leading to whole database performance degradation [ID 1532311.1]
=> As a workaround (until the change gets built in to 11.2.0.4 and 12c) you need to set _securefiles_concurrency_estimate = 50 before creating the tables.
1887235 - Increased buffer busy waits/contention on Oracle securefiles
To avoid performance problems caused by concurrency on securefiles increase the value of parameter to 50.
This will be the default value of _securefiles_concurrency_estimate for Oracle releases >11.2.0.3.
The parameter _simple_view_merging, can have quite disturbing impacts, make sure you are in the appropriate patch version before setting that parameter to false.
Check the information provided by Stefan in that message : http://scn.sap.com/thread/3452822
Best regards
In 1431798 - Oracle 11.2.0: Database Parameter Settings
you can find 2 more notes specifically referring to these parameters:
Note 1887235
Note 1915485
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