What is Parallel DML?

Dear all,

In a book, it says:
"In Oracle, you have the power of parallel DML and query to speed your
direct path along. In the code block that follows, notice the select statement has an embedded parallel query hint. Query and DML operation allows parallelism by generating multiple I/O processes that either draw more data into memory or write query. It requires that you first enable parallel DML in your session, using the alter session enable parallel DML statement, which must be executed at the beginning of the transaction if it is to be used at all during the transaction. The following code block demonstrates how you can mix and match hints in your direct-path insert statements:

ALTER SESSION ENABLE PARALLEL DML; INSERT /*+APPEND */ INTO spanky.employees NOLOGGING (select /*+PARALLEL(athena.employees,4) */ *  from athena.emplyees);

INSERT /*+PARALLEL(spanky.empoyees,4) */ INTO spanky.employees NOLOGGING
(select /*+PARALLEL(athena.employees,4) */ *  from athena.employees);
"

I don't fully understand the purpose and significance of using parallel DML yet, can anyone further explain this? What is difference between 'with' and 'without' parallel DML? Thanks in advance.

Dino Received on Fri Jul 20 2001 - 18:58:06 CDT