Decision to Parallelize

The following rule determines whether the INSERT operation should be parallelized in an INSERT SELECT statement:

The INSERT operation is executed in parallel if and only if at least one of the following is true:

  • The PARALLEL hint is specified after the INSERT in the DML statement.

  • The table being inserted into (the reference object) has a PARALLEL declaration specification.

  • An ALTER SESSION FORCE PARALLEL DML statement has been issued previously during the session.

The decision to parallelize the INSERT operation is independent of the SELECT operation, and vice versa.