One of the problems with Oracle data warehouses is their huge size.  For very large database warehouses, performing a database re-organization is impractical because of the amount of time required to export the data warehouse to tape, drop the Oracle database, and re-create the warehouse using Oracle's import utility.  Because of this time issue, the data warehouse manager must find alternative methods for insuring that our Oracle data warehouse remains well-tuned from a physical data perspective.

In an Oracle data warehouse, a large index may take a long amount of time to rebuild, and the prudent data warehouse administrator must carefully choose the right conditions that warrant an index rebuild.  If the very large database tables have been horizontally partitioned, where the large table is split into sub-tables according to date, we see that there will be several smaller indexes to replace a single, very large index. For details on using index partitioning, see Chapter 14, Oracle8 for the Warehouse.

In general, indexes will seldom required rebuilding in an Oracle data warehouse unless there has been a high amount of update or delete activity against the index columns.  SQL Insert operations that are common for loads of new warehouse data do not cause structural problems with the Oracle index structure.