Explanation/Reference:
Explanation:
* Oracle indexes can go into a UNUSABLE state after maintenance operation on the table or if the index is marked as 'unusable' with an ALTER INDEX command. A direct path load against a table or partition will also leave its indexes unusable.
Queries and other operations agains a table with unuable indexes will generate errors:
ORA-01502: index 'string.string' or partition of such index is in unusable state
* The following SQL will print out a list of alter commands that can be executed to fix unusable indexes:
Indexes:
SELECT 'alter index '||index_name||' rebuild tablespace '||tablespace_name ||';' FROM dba_indexes
WHERE status = 'UNUSABLE';