RE: [External] Wierd Parallel DDL Behaviour ?

Thanks Hemant.

Interestingly, if I remove /*+ parallel(4) */ and replace it with "parallel 4" at the statement level, it stops working. Any idea why this might be happening?

Gokul Gopal

-----Original Message-----
From: "Chitale, Hemant K" <Hemant-K.Chitale_at_sc.com> Sent: ‎16/‎12/‎2016 07:09
To: "gokulkumar.gopal_at_gmail.com" <gokulkumar.gopal_at_gmail.com>; "Oracle-L Group" <oracle-l_at_freelists.org> Subject: RE: [External] Wierd Parallel DDL Behaviour ?

>> create /*+ parallel(4) */ table t15
 

Since at least 7.3.4  

See the CREATE TABLE statement and the PARALLEL Clause in the 7.3.4 documentation available online http://docs.oracle.com/pdf/A32538_1.pdf (back then, Parallel Query was a licensed Option in the database)  

Hemant K Chitale      

From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Gokul Kumar Gopal Sent: Friday, December 16, 2016 4:07 AM
To: Oracle-L Group
Subject: [External] Wierd Parallel DDL Behaviour ?  

Hello,  

I am trying to understand the following run..  

sqlplus <user>/<pwd>_at_db  

SQL*Plus: Release 11.2.0.1.0 Production on Fri Dec 16 01:25:38 2016  

Copyright (c) 1982, 2010, Oracle. All rights reserved.    

Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production With the Partitioning, Real Application Clusters, Automatic Storage Management, OLAP, Data Mining and Real Application Testing options  

SQL> select * from v$mystat where rownum <= 1;  

       SID STATISTIC# VALUE
---------- ---------- ----------

       278 0 0  

SQL>
SQL>
SQL> alter session force parallel DDL;
 

Session altered.  

SQL> alter session force parallel DML;  

Session altered.  

SQL> alter session force parallel query;  

Session altered.  

SQL>
SQL> create table t15 as select * from dba_objects union all select * from dba_objects; ^C  

At this point, I had to stop the process as it created 289 sessions and was still running..  

I made some changes and re-ran..  

sqlplus <user>/<pwd>_at_db  

SQL*Plus: Release 11.2.0.1.0 Production on Fri Dec 16 01:29:34 2016  

Copyright (c) 1982, 2010, Oracle. All rights reserved.    

Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production With the Partitioning, Real Application Clusters, Automatic Storage Management, OLAP, Data Mining and Real Application Testing options  

SQL> alter session force parallel DDL;  

Session altered.  

SQL> alter session force parallel DML;  

Session altered.  

SQL> alter session force parallel query;  

Session altered.  

SQL>
SQL> set timing on
SQL>
SQL> select * from v$mystat where rownum <= 1;
 
       SID STATISTIC#      VALUE
---------- ---------- ----------
       278          0          0
 

Elapsed: 00:00:00.50
SQL>
SQL> create /*+ parallel(4) */ table t15 as select * from dba_objects union all select * from dba_objects;  

Table created.  

Elapsed: 00:00:08.02  

The highlighted part is the only changed I made, but I cannot explain why this worked with no additional sessions.. I have never seen this syntax mentioned anywhere but a casual try worked.  

Does anyone know how this works ?  

Rgds,
Gokul

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