Oracle
Database 11g adds interval partitioning, providing the ability to automatically generate
a new partition of a fixed interval or range when data to be inserted does not fit
into existing partition ranges.
Youcan also have two levels of partitions, called composite partitions, using a combination
of partition methods. Prior to Oracle Database 11g, you could partition using
a composite of range and hash partitioning. Oracle Database 11g adds the ability to
combine list partitioning with list, range, or hash partitioning, or range partitioning
with a different range partitioning scheme.
Basic Data Structures | 97
Oracle is smart enough to take advantage of partitions to improve performance in
two ways:
??? Oracle won??™t bother to access partitions that won??™t contain any data to satisfy
the query.
??? If all the data in a partition satisfies a part of the WHERE clause for the query,
Oracle simply selects all the rows for the partition without bothering to evaluate
the clause for each row.
Partitioned tables are especially useful in a data warehouse, in which data can be partitioned
based on the time period it spans.
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