Oracle Tips  by Burleson Consulting

The Data Warehouse Development Life Cycle

Parallelism And Oracle Data Warehousing

Parallel Index Building

SELECT /*+ FULL(employee_table) PARALLEL(employee_table, 4) */
employee_name
FROM
employee_table
SEE CODE DEPOT FOR FULL SCRIPT

If you are using SMP with many CPUs, you can issue a parallel request and leave it up to each Oracle instance to use its default degree of parallelism, as follows:

SELECT /*+ FULL(employee_table) PARALLEL(employee_table, DEFAULT, DEFAULT) */
employee_name
FROM
employee_table
SEE CODE DEPOT FOR FULL SCRIPT

The following several important init.ora parameters have a direct impact on parallel query:

* SORT_AREA_SIZE--The higher the value, the more memory available for individual sorts on each parallel process. Note that the SORT_AREA_SIZE parameter allocates memory for every query on the system that invokes a sort. For example, if a single query needs more memory and you increase the SORT_AREA_SIZE, all Oracle tasks will allocate the new amount of sort area, regardless of whether they will use all of the space.

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