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Query hidden parameters [message #602377]

Tue, 03 December 2013 13:52

juamd
Messages: 21
Registered: November 2011
Location: Colombia

Junior Member

Hi.

I am not able to get some hidden parameters from oracle, I need this parameters:

_always_semi_join
_b_tree_bitmap_plans
_partition_view_enabled
_gc_defer_time
_no_or_expansion
_optimizer_max_permutations

And I am using this query:

select par.ksppinm name,
val.ksppstvl value,
val.ksppstdf default_value
from x$ksppi par,
x$ksppcv val
where par.indx=val.indx;

But none of them appear

My db is started with spfile and my user has sysdba role.

Thanks.

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Re: Query hidden parameters [message #602378 is a reply to message #602377]

Tue, 03 December 2013 14:40

BlackSwan
Messages: 26757
Registered: January 2009
Location: SoCal

Senior Member

You should only ever be using hidden parameters under direction from Oracle Support.
Submit your question via Service Request to MOS.

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Re: Query hidden parameters [message #602531 is a reply to message #602377]

Thu, 05 December 2013 06:54

martijn
Messages: 286
Registered: December 2006
Location: Netherlands

Senior Member

I would try something like :

SQL> select * 
           from   x$kspvld_values  
           where  lower(NAME_KSPVLD_VALUES) like '%always_semi_join%';

ADDR           INDX    INST_ID PARNO_KSPVLD_VALUES NAME_KSPVLD_VALUES   ORDINAL_KSPVLD_VALUES VALUE_KSPVLD_VALUES  ISDEFAULT_KSPVLD_VALUES
-------- ---------- ---------- ------------------- -------------------- --------------------- -------------------- ----------------------------------------------------------------
B6A28818        501          1                2114 _always_semi_join                        1 HASH                 FALSE
B6A28818        502          1                2114 _always_semi_join                        2 MERGE                FALSE
B6A28818        503          1                2114 _always_semi_join                        3 NESTED_LOOPS         FALSE
B6A28818        504          1                2114 _always_semi_join                        4 CHOOSE               FALSE
B6A28818        505          1                2114 _always_semi_join                        5 OFF                  FALSE
SQL>

But keep in mind the words from Blackswan. You should be well aware of what you are doing to play around with hidden settings.
And...don't play around in production.

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Re: Query hidden parameters [message #602566 is a reply to message #602531]

Thu, 05 December 2013 13:44

juamd
Messages: 21
Registered: November 2011
Location: Colombia

Junior Member

Thanks guys.. that worked and by the way, we need to modify these parameters because of oracle support tells us in a document about siebel's performance.

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