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Parallel hint not working in an insert

Posted on 2008-10-16
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Last Modified: 2012-05-05
Here is my INSERT pseudo code.  How come parallel not working?  Working on another insert in the same database with same source table.  Thanks.

 INSERT /*+ append */ INTO BIG_TABLE
         SELECT   /*+ index (source_table my_idx1)  parallel_index(source_table, my_idx1,14)
                DISTINCT  ...
                    FROM
                  (SELECT /*+ index (source_table my_idx1)  parallel_index(source_table, my_idx1,14)
                                 from ....big query)
            where ...
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Question by:ewang1205
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by:sujith80
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what is the result of the following from sqlplus:

show parameter parallel
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by:ewang1205
ID: 22740846
Here is the results.  Parallel works on this server because some other parallel queries work fine.  I guess my query may be too complex.

SQL> show parameter parallel;

NAME                                 TYPE        VALUE
------------------------------------ ----------- ---------
fast_start_parallel_rollback         string      LOW
parallel_adaptive_multi_user         boolean     TRUE
parallel_automatic_tuning            boolean     FALSE
parallel_execution_message_size      integer     2152
parallel_instance_group              string
parallel_max_servers                 integer     385
parallel_min_percent                 integer     0
parallel_min_servers                 integer     0
parallel_server                      boolean     FALSE
parallel_server_instances            integer     1
parallel_threads_per_cpu             integer     2
recovery_parallelism                 integer     0
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by:ewang1205
ID: 22744003
Might be limitation on parallel.  Will parallel still work if I have ROLLUP function in the SQL query?  Thanks.
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Author Comment

by:ewang1205
ID: 22757808
Looks like parallel doesn't work on ROLLUP function in the SQL query.  I tried without ROLLUP function in the SQL query and parallel hint works.  
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by:sujith80
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the settings looks fine to me.

Parallelism doesnt work for query part or the insert part? or for both?
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Author Comment

by:ewang1205
ID: 22778367
Parallelism doesnt work for query part .  
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ewang1205 earned 0 total points
ID: 22835824
I conclude the parallel doesn't always work.  It doesn't work where the query is too complex.  In my case, the query has analytical function called rollup, the parallel  doesn't work.  I will accept my answer as solution if there is no other objections.  Thanks.
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