SQL> 
SQL> 
SQL> show user
USER is "ANDREY"
SQL> 
SQL> 
SQL> create table TEST
  2  (
  3    col1 VARCHAR2(50),
  4    col2 NUMBER,
  5    uniq TIMESTAMP(6) default sysdate not null
  6  );

Table created.

SQL> 
SQL> create index IF on TEST (COL2);

Index created.

SQL> create index IND1 on TEST (COL1 DESC);

Index created.

SQL> create unique index IND1UNIQ on TEST (COL1);

Index created.

SQL> 
SQL> 
SQL> insert into test select distinct table_name , to_char(sysdate,'ss'), sysdate from dba_tables where table_name not in ( select col1 from test ) ;

4147 rows created.

SQL> 
SQL> commit;

Commit complete.

SQL> 
SQL> EXEC  dbms_stats.gather_table_stats ( ownname => user, tabname => 'TEST' , estimate_percent => 100 , method_opt => 'FOR ALL INDEXED COLUMNS SIZE 10', CASCADE=> TRUE);

PL/SQL procedure successfully completed.

SQL> 
SQL> 
SQL> 
SQL> set autot on
SQL> 
SQL> select /*+ index( t IND1UNIQ )*/  col1 from test t;

COL1                                                                            
--------------------------------------------------                              
ICOL$                                                                           
CLU$                                                                            
UGROUP$                                                                         
...
...
..
MRAC_OLAP2_AW_DIMENSIONS_T                                                      
SDO_TXN_IDX_EXP_UPD_RGN                                                         
SDO_TOPO_MAPS                                                                   
SDO_TOPO_TRANSACT_DATA                                                          
SDO_GEOR_SYSDATA_TABLE                                                          
SDO_GEOR_PLUGIN_REGISTRY                                                        
OLS_DIR_BUSINESSES                                                              

4147 rows selected.


Execution Plan
----------------------------------------------------------                      
Plan hash value: 1357081020                                                     
                                                                                
--------------------------------------------------------------------------      
| Id  | Operation         | Name | Rows  | Bytes | Cost (%CPU)| Time     |      
--------------------------------------------------------------------------      
|   0 | SELECT STATEMENT  |      |   100 |  1900 |     2   (0)| 00:00:01 |      
|   1 |  TABLE ACCESS FULL| TEST |   100 |  1900 |     2   (0)| 00:00:01 |      
--------------------------------------------------------------------------      


Statistics
----------------------------------------------------------                      
        217  recursive calls                                                    
          0  db block gets                                                      
        343  consistent gets                                                    
          0  physical reads                                                     
          0  redo size                                                          
     106755  bytes sent via SQL*Net to client                                   
       3400  bytes received via SQL*Net from client                             
        278  SQL*Net roundtrips to/from client                                  
          3  sorts (memory)                                                     
          0  sorts (disk)                                                       
       4147  rows processed                                                     

SQL> 
SQL> 
SQL> spool off