BitMapScan performance degradation

Hi All,

    I have some problems with my sql query :

select distinct
INTEGER_VALUE,DATE_VALUE,EI_ID,VALUE_TYPE,FLOAT_VALUE,ID,TEXT_VALUE,CATEGORY_ID,STRING_VALUE,CATEGORYATTR_ID,NAME from
((( select d_attribute as reqin2 where reqin2.CATEGORYATTR_ID = 1041947543 AND reqin2.TEXT_VALUE ilike '%autrefois%'
andei_id in ( select distinct ei_id as EIID from MPNG2_ei_attribute as reqin3 where reqin3.NAME =
'CategoryID-1084520156'AND reqin3.STRING_VALUE = '1084520156' )  )  ) ) ) as req0 join MPNG2_ei_attribute on req0.eiid
=MPNG2_ei_attribute.ei_id   order by ei_id asc; 

    When enable_bitmapscan is enabled this query cost 51893.491 ms and when
is disabled 117.709 ms. But i heard bitmapscan feature improved
performance, can you help me ?

    You can read two results of EXPLAIN ANALYZE command here :
http://sharengo.org/explain.txt

Best Regards,
Jérôme.

--
Jérôme BENOIS
Open-Source : http://www.sharengo.org
Corporate : http://www.argia-engineering.fr
JabberId : jerome.benois AT gmail.com