Varray Problem

[B3D70]

Hi there ...
I have a table with a Varray Columns.
When I used a select operation without access the varray columns the explain plan show fine.. cost = 4
but when I access the Varray columns then I got the cost = 1310

Why ? What happend ? and why oracle did it ?
Someone can explain it to me ?
or how shoud I optimized it ?

this is my query without varrary
SELECT   a.id,
         a.address
FROM     my_table a

Operation                       Object Name     Rows    Bytes   Cost    
SELECT STATEMENT Hint=CHOOSE            3               4                                       
  SORT GROUP BY                         3       60      4                                       
    TABLE ACCESS FULL   MY_TABLE        9       180     2                                       


this is my query with varrary
SELECT   a.id,
         a.address
FROM     my_table a, TABLE(a.no_of_car) b

Operation                     Object Name       Rows    Bytes   Cost    
SELECT STATEMENT Hint=CHOOSE            3               1310                                    
  SORT GROUP BY                         3       459     1310                                    
    NESTED LOOPS                                73 K    10 M    101                                     
      TABLE ACCESS FULL MY_TABLE        9       1 K     2                                       
      COLLECTION ITERATOR PICKLER FETCH                                                                 


regards
kang bedjo