Till oracle 12c, For doing DML transactions in parallel, we need to enable PDML (parallel DML) at session level.
I.e before any DML statement, we need to issue below statement.

In oracle 12c, it introduced a hint for parallel dml, ENABLE_PARALLEL_DML , which we can use directly inside the dml sql statement. No need to issuing alter session statement.

It will look as below:

Lets compare the execution plan with and without ENABLE_PARALLEL_DML

WITHOUT ENABLE_PARALLEL_DML:

 

WITH ENABLE_PARALLEL_DML hint:

We can see, With this ENABLE_PARALLEL_DML hint, even without the alter session command, PDML is enabled.

Similarly DISABLE_PARALLEL_DML for disabling the PDML.

 

 

SEE ALSO:

New features of oracle 12.2.