Indexing Partitions
Local indexes on partitions reflect the structure of the underlying table and in general are easier
to maintain than nonpartitioned or global partitioned indexes. Local indexes are equipartitioned
with the underlying partitioned table; in other words, it is partitioned on the same columns as the
572 Oracle Database 11g DBA Handbook
underlying table and therefore has the same number of partitions and the same partition bounds
as the underlying table.
Global partitioned indexes are created irrespective of the partitioning scheme of the underlying
table and can be partitioned using range partitioning or hash partitioning. In this section, first I??™ll
show you how to create a local partitioned index; next, I??™ll show you how to create both rangepartitioned
and hash-partitioned global indexes. In addition, I??™ll show you how to save space in a
partitioned index by using key compression.
Creating Local Partitioned Indexes A local partitioned index is very easy to set up and maintain
because the partitioning scheme is identical to the partitioning scheme of the base table. In other
words, the number of partitions in the index is the same as the number of partitions and subpartitions
in the table; in addition, for a row in a given partition or subpartition, the index entry is always
stored in the corresponding index??™s partition or subpartition.
Figure 16-1 shows the relationship between a partitioned local index and a partitioned table.
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