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May 4th

Question and Answer

Chris Saxon

Thanks for the question, Abhiraj.

Asked: October 17, 2017 - 7:03 am UTC

Last updated: October 17, 2017 - 10:35 am UTC

Version: 11.2.0.4.0

Viewed 1000+ times

You Asked

Will the below hidden parameter have any issues. Database version : 11.2.0.4.0

_always_anti_join
off
  
_always_semi_join
off
  
_disk_sector_size_override
TRUE
  
_hash_join_enabled
FALSE
  
_kgl_large_heap_warning_threshold
204857600

and Chris said...

Maybe.

As MOS note 315631.1 says:

It is never recommended to modify these hidden parameters without the assistance of Oracle Support.
Changing these parameters may lead to serious corruption issues, high performance degradation and other problems in the database.


Their behaviour is undocumented. So may change without warning. And lead to unexpected outcomes.

Leave them alone unless support tells you otherwise.

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