We??™ve divided the discussion in the following subsections into two categories:
database parallelization and data warehousing.
Database Parallelization
Database tasks implemented in parallel speed up querying, tuning, and maintenance
of the database. By breaking up a single task into smaller tasks and assigning each
subtask to an independent process, you can dramatically improve the performance of
certain types of database operations. Examples of query features implemented in parallel
include:
??? Table scans
??? Nested loops
??? Sort merge joins
??? GROUP BYs
??? NOT IN subqueries (anti-joins)
??? User-defined functions
??? Index scans
??? Select distinct UNION and UNION ALL
??? Hash joins
??? ORDER BY and aggregation
??? Bitmap star joins
??? Partition-wise joins
??? Stored procedures (PL/SQL, Java, external routines)
In addition to parallel query, many other Oracle features and capabilities are parallelized.
Parallel operations are further identified and described in Chapter 7.
Data Warehousing and Business Intelligence
While parallel features improve the overall performance of the Oracle database, Oracle
also has particular performance enhancements for business intelligence and data
warehousing applications.
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