In addition, you have the option to turn logging off to increase performance of the direct load insert statement. Direct load inserts require more space than conventional path inserts because they ignore existing free space lists and append data beyond the high water mark . Conventional path inserts reuse free space in the current data segment below the high water mark. Direct load inserts can not be used if there are any global indexes or referential constraints on the table. Conventional path inserts are also unable to execute in parallel.
Parallelism increases query performance by splitting the work among multiple CPUs.
Oracle8 takes parallelism one step further by allowing you to parallelize insert, update and delete statements. Parallel DML is particularly useful for decision support applications that contain large amounts of data. Update and delete statements can only be parallelized on partitioned tables. They can not access individual partitions or non-partitioned tables in parallel. Unlike update and delete statements, insert statements can be parallelized on both non-partitioned and partitioned tables.