Local partitioned indexes are easier to manage than other types of partitioned indexes.
They also offer greater availability and are common in DSS environments. The reason
for this is equipartitioning: each partition of a local index is associated with exactly one
partition of the table. This enables Oracle to automatically keep the index partitions in
sync with the table partitions, and makes each table-index pair independent. Any
actions that make one partition's data invalid or unavailable only affect a single
partition.

Local partitioned indexes support more availability when there are partition or
subpartition maintenance operations on the table. A type of index called a local
nonprefixed index is very useful for historical databases. In this type of index, the
partitioning is not on the left prefix of the index columns.

You cannot explicitly add a partition to a local index. Instead, new partitions are added
to local indexes only when you add a partition to the underlying table. Likewise, you
cannot explicitly drop a partition from a local index. Instead, local index partitions are
dropped only when you drop a partition from the underlying table.

A local index can be unique. However, in order for a local index to be unique, the
partitioning key of the table must be part of the index’s key columns. Unique local
indexes are useful for OLTP environments.

局部索引分区与表分区同步，一一对应.
局部非前缀索引对于历史数据库非常有用.
不能显示的添加删除分区于局部索引.
表的分区键需为索引键的一部分才能构建唯一的局部索引，对于OLTP环境非常有用.