Unusable partitions

How do I repair unusable partitions?

Run this SQL command to determine which index partition is unusable.

SELECT p.index_name, p.partition_name, p.status

FROM dba_ind_partitions p, dba_indexes i
WHERE p.index_name = i.index_name AND
p.status <>'USABLE' AND
p.index_owner = 'ESECDBA';

Then run this command to rebuild the index.

alter index rebuild partition