Cause
Only ALLOCATE EXTENT and DEALLOCATE UNUSED may be specified in ALTER TABLE MODIFY PARTITION for a Hash partition.
Only ALLOCATE EXTENT and DEALLOCATE UNUSED may be specified in ALTER TABLE MODIFY PARTITION for a Hash partition.
Remove the INDEXING clause from the statement.
Try the following links for this error:
http://docs.oracle.com/cd/E16655_01/server.121/e26079/e12700.htm
https://community.oracle.com/message/3345878
https://community.oracle.com/message/2304527
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