Just to emphasise the point the Bruno made - I have a partitioned table called pt_range with 3 partitions, which happens to have a local index called pt_range. Here's the output from your query (reduced to a subset of the columns) when I specify my schema name and the table name, plus a non-null :object_type and null :sub_object

TABLE_NAME                OWNER             OBJECT_NAME          OWNER             OBJECT_TYPE             COMMENTS
------------------------- ----------------- -------------------- ----------------- ----------------------- --------------------------------
PT_RANGE                  TEST_USER         PT_RANGE             TEST_USER         TABLE                   This is a partitioned table
                          TEST_USER         PT_RANGE             TEST_USER         TABLE PARTITION         This is a partitioned table
                          TEST_USER         PT_RANGE             TEST_USER         TABLE PARTITION         This is a partitioned table
                          TEST_USER         PT_RANGE             TEST_USER         TABLE PARTITION         This is a partitioned table
                          TEST_USER         PT_RANGE             TEST_USER         INDEX                   This is a partitioned table
                          TEST_USER         PT_RANGE             TEST_USER         INDEX PARTITION         This is a partitioned table
                          TEST_USER         PT_RANGE             TEST_USER         INDEX PARTITION         This is a partitioned table
                          TEST_USER         PT_RANGE             TEST_USER         INDEX PARTITION         This is a partitioned table

8 rows selected.

Note that the query has picked up the table and its index and the partitions of the table and index. And the comment that's been reported 8 times is the comment associated with the table.

And this is the result running Bruno's query (with the typo - the extra "join" - deleted and, again, a subset of columns):

TABLE_NAME                OWNER             OBJECT_NAME          OWNER             OBJECT_TYPE             COMMENTS
------------------------- ----------------- -------------------- ----------------- ----------------------- --------------------------------
PT_RANGE                  TEST_USER         PT_RANGE             TEST_USER         TABLE                   This is a partitioned table

1 row selected.

Regards

Jonathan Lewis