Caching - The same cacheModel with similar queries

[Guido García Bernardo]

Hi,
I've two questions regarding with caching.
Is caching useful when using two similar queries (the second one being 
the first one plus a where clause) ?

   <statement id="getAreas" resultMap="area_result" 
cacheModel="areas-cache">
   select * from AREAS
   </statement>
   
   <statement id="getArea" resultMap="area_result" 
cacheModel="areas-cache">
   select * from AREAS where codigo = #value#
   </statement>

   <cacheModel id="areas-cache" readOnly="true" type="MEMORY">
       <flushInterval hours="24" />
       <property name="reference-type" value="WEAK" />       
   </cacheModel>

Is there any problem when using WEAK references? 
(http://www.mail-archive.com/ibatis-user-java@incubator.apache.org/msg01190.html)

Thank you.
Guido García Bernardo.