How Oracle sets PARALLEL_QUERY_DEFAULT_DOP

  • From: "Hameed, Amir" <amir.hameed@xxxxxxxxxxxxxxx>
  • To: "oracle-l@xxxxxxxxxxxxx" <oracle-l@xxxxxxxxxxxxx>
  • Date: Thu, 29 Jul 2021 22:38:39 +0000

Hi,
This is a three-node RAC environment running an Oracle EBS database. The 
database version is 11.2.0.4 and the OS is Solaris 11. The While investigating 
the execution plan of a SQL statement (a standard EBS statement), I ran the 
following statement for a particular SQL_ID:
SELECT
   inst_id,
   sql_id,
   child_number,
   id,
   name,
   isdefault,
   value
FROM
   gv$sql_optimizer_env
WHERE
   sql_id       = '&m_sql_id' AND
   isdefault    = 'NO'
ORDER BY
   inst_id,
   name
;

   INST_ID SQL_ID        CHILD_NUMBER         ID NAME                           
          ISD VALUE
---------- ------------- ------------ ---------- 
---------------------------------------- --- -------------------------
         1 308zt411qcsyq            0         49 _b_tree_bitmap_plans           
          NO  false
                                    0         60 _fast_full_scan_enabled        
          NO  false
                                    0         92 _like_with_bind_as_equality    
          NO  true
                                    0         25 _pga_max_size                  
          NO  2097152 KB
                                    0         18 _sort_elimination_cost_ratio   
          NO  5
                                    0        167 optimizer_secure_view_merging  
          NO  false
                                    0        273 parallel_force_local           
          NO  true
                                    0        256 parallel_query_default_dop     
          NO  28

         3 308zt411qcsyq            0         49 _b_tree_bitmap_plans           
          NO  false
                                    0         60 _fast_full_scan_enabled        
          NO  false
                                    0         92 _like_with_bind_as_equality    
          NO  true
                                    0         25 _pga_max_size                  
          NO  2097152 KB
                                    0         18 _sort_elimination_cost_ratio   
          NO  5
                                    0        167 optimizer_secure_view_merging  
          NO  false
                                    0        273 parallel_force_local           
          NO  true


15 rows selected.

I have checked all the tables involved in the query and none of them have any 
DOP set. I am curious to know how Oracle is setting this parameter?

Thanks,
Amir

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