Recheck condition...

Hello,

I think that my query is as much tuned as possible can. However I am
baffled by the "recheck condition" that always follow my index scan. Is
this something normal or can I get rid of it somehow?

"HashAggregate (cost=2141.07..2141.16 rows=4 width=38)"
" -> Result (cost=0.00..2141.03 rows=4 width=38)"
" -> Append (cost=0.00..2140.99 rows=4 width=38)"
" -> Seq Scan on message_copies (cost=0.00..0.00 rows=1
width=68)"
" Filter: ((date_part('day'::text, msg_date_rec) =
ANY ('{6}'::double precision[])) AND (date_trunc('day'::text,
msg_date_rec) = ANY ('{"2012-01-06 00:00:00"}'::timestamp without time
zone[])) AND (((((pos_georef1)::text || (pos_georef2)::text) ||
(pos_georef3)::text) || (pos_georef4)::text) = ANY
('{MKPM2648,MKPM2649,MKPM2650}'::text[])) AND (src_id = ANY
('{1,2,3,4,5,6,7,8,9,10}'::integer[])))"
" -> Bitmap Heap Scan on message_copies_wk0
message_copies (cost=139.41..2140.99 rows=3 width=28)"
" *Recheck Cond*: ((date_trunc('day'::text, msg_date_rec) = ANY
('{"2012-01-06 00:00:00"}'::timestamp without time zone[])) AND (src_id
= ANY ('{1,2,3,4,5,6,7,8,9,10}'::integer[])) AND (((((pos_georef1)::text
|| (pos_georef2)::text) || (pos_georef3)::text) || (pos_georef4)::text)
= ANY ('{MKPM2648,MKPM2649,MKPM2650}'::text[])))"
" Filter: (date_part('day'::text, msg_date_rec) = ANY
('{6}'::double precision[]))"
" -> Bitmap Index Scan on
idx_message_copies_wk0_date_src_pos (cost=0.00..139.41 rows=507 width=0)"
" Index Cond: ((date_trunc('day'::text,
msg_date_rec) = ANY ('{"2012-01-06 00:00:00"}'::timestamp without time
zone[])) AND (src_id = ANY ('{1,2,3,4,5,6,7,8,9,10}'::integer[])) AND
(((((pos_georef1)::text || (pos_georef2)::text) || (pos_georef3)::text)
|| (pos_georef4)::text) = ANY ('{MKPM2648,MKPM2649,MKPM2650}'::text[])))"

Kind Regards
Yiannis