By default, the following operations on partitions on a heap-organized table mark all global indexes as unusable:
ADD (HASH) COALESCE (HASH) DROP EXCHANGE MERGE MOVE SPLIT TRUNCATE
These indexes can be maintained by appending the clause UPDATE INDEXES to the SQL statements for the operation. Note, however, that appending the UPDATE INDEXES clause maintains the global index as part of the partition maintenance operation, potentially elongating the run time of the operation and increasing the resource requirements.
The two advantages to maintaining global indexes are:
The index remains available and online throughout the operation. Hence no other applications are affected by this operation.
The index does not have to be rebuilt after the operation.
The global index maintenance for DROP and TRUNCATE is implemented as metadata-only operation.
Figure 2-7 offers a graphical view of global partitioned indexes.
For more information about global partitioned indexes, refer to "Global Partitioned Indexes".