SQL> 
SQL> -- What happen to global, local indexes when a partition is truncated?
SQL> 
SQL> drop table part_range_hash;
drop table part_range_hash
           *
ERROR at line 1:
ORA-00942: table or view does not exist 


SQL> 
SQL> create table part_range_hash (c1 number(3), c2 varchar2(2), c3 char(1))
  2  partition by range (c1)
  3  subpartition by hash (c3)
  4  (partition p1 values less than (100)
  5   (subpartition p1_d1,
  6    subpartition p1_d2,
  7    subpartition p1_d3),
  8  partition p2 values less than (200)
  9   (subpartition p2_d1,
 10    subpartition p2_d2,
 11    subpartition p2_d3),
 12  partition p3 values less than (maxvalue)
 13   (subpartition p3_d1,
 14    subpartition p3_d2,
 15    subpartition p3_d3)
 16  );

Table created.

SQL> 
SQL> create index part_range_hash_pk on part_range_hash(c1,c3) local;

Index created.

SQL> create index part_range_hash_global on part_range_hash(c2);

Index created.

SQL> 
SQL> alter table part_range_HASH add constraint part_range_HASH_pk primary key (c1, c3);

Table altered.

SQL> insert into part_range_HASH values(50, 'a', 'a');

1 row created.

SQL> insert into part_range_HASH values(150, 'b', 'b');

1 row created.

SQL> insert into part_range_HASH values(250, 'b', 'c');

1 row created.

SQL> commit;

Commit complete.

SQL> 
SQL> alter table part_range_HASH truncate partition p1;

Table truncated.

SQL> 
SQL> -- Global index becomes unusable
SQL> select index_name, index_type, uniqueness, status, partitioned from user_indexes
  2         where table_name='PART_RANGE_HASH';

INDEX_NAME                     INDEX_TYPE                  UNIQUENES STATUS     
------------------------------ --------------------------- --------- --------   
PAR                                                                             
---                                                                             
PART_RANGE_HASH_GLOBAL         NORMAL                      NONUNIQUE UNUSABLE   
NO                                                                              
                                                                                
PART_RANGE_HASH_PK             NORMAL                      NONUNIQUE N/A        
YES                                                                             
                                                                                

SQL> -- Local index remain usable
SQL> select partition_name, subpartition_name, status
  2         from user_ind_subpartitions where index_name='PART_RANGE_HASH_PK';

PARTITION_NAME                 SUBPARTITION_NAME              STATUS            
------------------------------ ------------------------------ --------          
P1                             P1_D1                          USABLE            
P1                             P1_D2                          USABLE            
P1                             P1_D3                          USABLE            
P2                             P2_D1                          USABLE            
P2                             P2_D2                          USABLE            
P2                             P2_D3                          USABLE            
P3                             P3_D1                          USABLE            
P3                             P3_D2                          USABLE            
P3                             P3_D3                          USABLE            

9 rows selected.

SQL> 
SQL> -- As long as the global index is unusable, no DML is possible.
SQL> insert into part_range_HASH values(50, 'a', 'a');
insert into part_range_HASH values(50, 'a', 'a')
*
ERROR at line 1:
ORA-01502: index 'SH.PART_RANGE_HASH_GLOBAL' or partition of such index is in 
unusable state 


SQL> insert into part_range_HASH values(350, 'b', 'c');
insert into part_range_HASH values(350, 'b', 'c')
*
ERROR at line 1:
ORA-01502: index 'SH.PART_RANGE_HASH_GLOBAL' or partition of such index is in 
unusable state 


SQL> 
SQL> -- Unless you skip the unusable "non-unique" indexes
SQL> alter session set skip_unusable_indexes=true;

Session altered.

SQL> insert into part_range_HASH values(50, 'a', 'a');

1 row created.

SQL> insert into part_range_HASH values(350, 'b', 'c');

1 row created.

SQL> commit;

Commit complete.

SQL> 
SQL> -- rebuild the global index
SQL> alter index part_range_hash_global rebuild;

Index altered.

SQL> 
SQL> drop table part_range_hash;

Table dropped.

SQL> alter session set skip_unusable_indexes=false;

Session altered.

SQL> 
SQL> spool off