What Can Be Parallelized?
Oracle can parallelize far more than simple queries. The list of operations that can be
parallelized using block-range parallelism includes the following:
??? Tablespace creation
??? Index creation and rebuilds
??? Online index reorganizations and rebuilds
??? Index-organized table reorganizations and movements
??? Table creation, such as summary creation using CREATE TABLE...AS SELECT
??? Partition-maintenance operations, such as moving and splitting partitions
??? Data loading
??? Integrity constraints imposing
??? Statistics gathering (automatically gathered since Oracle Database 10g)
??? Backups and restores (including very large files in Oracle Database 11g)
??? DML operations (INSERT, UPDATE, DELETE)
??? Query processing operations
??? OLAP aggregate (as of Oracle Database 10g)
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Oracle can also provide the benefits of parallelism to individual processing steps for
queries. The specific features of query processing that may be parallelized include:
??? Table scans
??? Nested loops
??? Sort merge joins
??? Hash joins
??? Bitmap star joins
??? Index scans
??? Partition-wise joins
??? Anti-joins (NOT IN)
??? SELECT DISTINCT
??? UNION and UNION ALL
??? ORDER BY
??? GROUP BY
??? Aggregations
??? Import
??? User-defined functions
Degree of parallelism
An Oracle instance has a pool of parallel execution (PE) processes that are available to
the database users.
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