Enable parallel processing

Question

Hello,
I'm trying to enable parallel processing at the session level to force parallel processing on all DML and DDL statements regardless of object definition or lack of hints for DML. I thought the following would do the trick but it's not working. Wondering if I'm missing an instance setting. Thanks for any advice.
alter session force parallel ddl parallel 2;
alter session force parallel dml parallel 2;
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 160
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

Answer 1

I think I see the problem. The statement that I was looking to force parallel processing was an alter table add col with default value. Reading the documentation :) and it states that the alter table statement can only be parallelized for partitioned tables - the table in question is not partitioned. Documentation also states that even with DML parallel enabled the DML operation may still execute serially if there are no parallel hints or no tables with a parallel attribute or if restrictions on parallel operations are violated, i.e. Parallel DML operations cannot be done on tables with triggers.
The problem for me is that I'm dealing with a 3rd party vendor script that I do not want to modify it (very long, complex PL/SQL with dynamic SQL), among other things the script alters high volume tables with default values, before it alters the table it renames it as table_old and then re-creates as ctas from old, so enabling parallel at the object level is only viable if I modify the script. Same thing with hints.