Explanation:
The statement ALTER TABLE sales MOVE PARTITION sal_q1 TABLESPACE EXAMPLE, won't have a UPADATE INDEXES clause. By default, many table maintenance operations on partitioned tables invalidate (mark UNUSABLE) the corresponding indexes or index partitions. You must then rebuild the entire index or, in the case of a global index, each of its partitions. The database lets you override this default behavior if you specify UPDATE INDEXES in your ALTER TABLE statement for the maintenance operation. Specifying this clause tells the database to update the index at the time it executes the maintenance operation DDL statement.
REF.:
Oracle® 10g Administrator Guide, 17-24

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