H.2.1.2 PARALLEL_DML

Limitations in Using Parallel DML

A Parallel DML operation's lock requirements are very different from the serial DML requirements. For these and other reasons, the database imposes some restrictions on Parallel DML operations.

One such restriction is that while a single transaction can contain multiple parallel DML statements that modify different tables after a parallel DML statement modifies a table no subsequent statement (DML or query) can access the same table again in the same transaction. For this reason, Parallel DML is disabled regardless of your parameter settings, for any allocation rule that both debit and credit the same table. For allocation rules that both debit and credit the same table and which you want to ensure run in parallel, you divide your one allocation rule into two rules (one rule for the debit side and one rule for the credit side).

Parallel DML cannot be set (regardless of the parameter settings) for any allocation rule where the Output tables (Credit/Debit) are the same as the Source/Driver tables.

For more information regarding the restrictions on Parallel DML, see the Oracle Database Data Warehousing Guide.