Parallel_max_server on the parallel implementation and parameters

Posted on 2009-07-02 filed under: Oracle (RSS) 21 views

Parallel_max_server on the parallel implementation and parameters

rn
parallel_max_server parameters will be restricted to the parallel execution, the current value of the parameter 5
SQL> show parameter parallel

rn
NAME TYPE VALUE
------------------------------------ ----------- --- ---------
parallel_max_servers integer 5

rn
Parallel test form time to 8
SQL> alter table tt parallel 8;

rn
Then run a query
SQL> select * from tt;
...

rn
In another window, query the view v $ px_session to check the number of parallel execution
select * from v $ px_session

sid serial # qcsid
10,610
18 29 10
23,310
22,310
21,310
20,310

rn
Can see that a total of six session, the other five session is derived from the SID 10. Parallel line that will only reach 5 degrees.

rn
Parallel_max_server now be revised to 8, the implementation of the above steps again, we can see a total of nine session, the other 8 are generated by the parallel query.

rn
The reason to do this test, mainly in the first work will be read parallel to the high degree, but did not confirm the value of parallel_max_servers a result, the value of degree higher than the parallel_max_servers, this degree does not work in practice. Should also improve the value of parallel_max_servers parallel in order to comply with the requirements.

rn