How to fix ORA-01502: index or partition of such index is in usable state?

Question

Greetings,
I received the ORA-01502: index or partition of such index is in un-usable state from one of our Oracle forms, and the problem was caused by using SQL Loader w/ the "DIRECT" load option. As a result of that, the system won't allow any updates including insert/delete to the problematic table w/ the index in un-usable state. I am trying to fix the problem but so far no luck:
When I tried to delete the duplicate rows from the table, I received the ORA-01502: index or partition of such index is in un-usable state error message;
When I tried to rebuild the index by using the following command:
ALTER INDEX index_name REBUILD
I received the "ORA-01452: cannot CREATE UNIQUE INDEX; duplicate keys found
Any help, suggestions or advice on this would be greatly appreciated.
Thanks millions in advance!

Answer 1

The duplicate key rows were inserted to the database by using the DIRECT parameter of the sql loader to specify direct path loading which bypasses integrity constraints. Since the issue exists in our production database and I am primarily an A/P w/ some responsibilities of DBA , I could really use your help to fix our production problem. I would really appreciate if you or any other guru could review my plan and code below for the fixes followed w/ some questions and give me your feedback/comments/suggestions as soon as possible:
1 - Drop the offending index by using the following command:
DROP INDEX <offending index name>
2 - Run the following script to detect duplicate rows:
SELECT *
FROM <Table_Name> A
WHERE
A.rowid >
any(SELECT B.rowid FROM <Table_Name> B
WHERE
B.KEY1 = A.KEY1
and
B.KEY2 = A.KEY2
and
B.KEY3 = A.KEY3
and
B.KEY4 = A.KEY4
3.  Run the following script to remove the duplicates:
DELETE
FROM <Table_Name> A
WHERE
A.rowid >
any(SELECT B.rowid FROM <Table_Name> B
WHERE
B.KEY1 = A.KEY1
and
B.KEY2 = A.KEY2
and
B.KEY3 = A.KEY3
and
B.KEY4 = A.KEY4
4 - Rebuild the index by using the following line command:
ALTER INDEX index_name REBUILDBut wait, how about data? Don't I need to back up and reload the data? Do I need to drop and recreate the table? Anything else I should be taking into considerations?
p.s. Although, we only have a total of 35,736 rows of data from this table, but I want to make sure I do it right the first time.
Thanks a lot and any/all the help!