Oracle in a Nutshell

Parallel execution hints

The following hints control the use of parallel execution for data warehousing type queries:

PARALLEL( table, [ integer | DEFAULT][,{ integer | DEFAULT}])

Specifies the degree of parallelism of the SQL operation on table. The first parameter specifies the degree of parallelism on the table; the second, optional parameter (new with Oracle 9i) specifies how the table is to be split between instances of the database in a Real Application Clusters implementation. The value DEFAULT indicates that the query should use the degree of parallelism set with the initialization parameter.

NOPARALLEL( table )

Overrides any parallelism setting and prevenst parallel operations on table.

PQ_DISTRIBUTE( table [,] outer_distribution, inner_distribution )

Specifies how rows of joined tables should be distributed between producer and consumer query servers. The outer_distribution and inner_distribution keyword pair can have six value combinations:

Hash, Hash

Broadcast, None

None, Broadcast

Partition, None

None, Partition

None, None

PARALLEL_INDEX( table, [ integer | DEFAULT][,{ integer | DEFAULT}])

Specifies the number of concurrent servers that can be used for parallel index range scans. The keywords have the same meaning as the keywords for the PARALLEL hint.

NOPARALLEL_INDEX( table )

Overrides any parallel setting and prevents parallel index scans.