Oracle8 introduced a further mechanism called a parallel bitmap star join, which uses
bitmap indexes on the foreign keys to the dimension tables to speed star joins involving
a large number of dimension tables.
Materialized views
Since Oracle8i, materialized views have provided another means of achieving a significant
speedup of query performance. Summary-level information derived from a
fact table and grouped along dimension values is stored as a materialized view. Queries
that can use this view are directed to the view, transparently to the user and the
SQL they submit. Oracle has continued to improve optimizer usage of materialized
views with each new release of the database.
Analytic functions
A growing trend in Oracle and other databases is inclusion of SQL-accessible analytic
and statistical functions in the database. Oracle first introduced such capabilities in
Oracle8i with the CUBE and ROLLUP functions. Today, the functionality provided
also includes ranking functions, windowing aggregate functions, lag and lead
functions, reporting aggregate functions, statistical aggregates, linear regression,
descriptive statistics, correlations, crosstabs, hypothesis testing, distribution fitting,
and Pareto analysis.
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