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Oracle Tips by Burleson |
OCP Instructors Guide for
Oracle DBA Certification
Chapter 5 - Oracle Database
Objects
Index Partitioning
Oracle also allows you to create
range-partitioned indexes. Oracle uses the same range-partitioning
algorithm as it does for tables. Like partitioned tables, Oracle
maps rows to specific index partitions based on the index’s
partitioning key. The partitioning key of an index must include one
or more of the columns that define the index. This allows
administrators to create an index that contains multiple columns but
partitions the index on a subset of those columns. An index
partition is defined exactly like its partitioned table counterpart;
an upper boundary of partitioning key values is hard-coded into each
tablespace specification.
Equi-Partitioned Objects
An index and table that has the same number of
partitions are said to be equi-partitioned. Multiple tables and
multiple indexes can be equi-partitioned if they meet Oracle’s equi-partition
specifications. Please refer to the Oracle Server Concepts manual
for a more complete listing of equi-partitioning specifications.
Equi-partitioned objects improve query
performance by reducing the number of rows being sorted and joined.
The Oracle optimizer is also partition aware. If the optimizer
determines that a single index/table partition combination will
satisfy a query, it will create an execution plan that accesses the
single index and table partition.
The above text is
an excerpt from:
OCP Instructors Guide for Oracle DBA Certification
A Study Guide to Advanced Oracle Certified Professional Database
Administration Techniques
ISBN 0-9744355-3-8
by Christopher T. Foot
http://www.rampant-books.com/book_2003_2_OCP_print.htm
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