function executes sql 100 times longer it should

Hello, list.

I have one simple SQL function returning result set that takes around 3
seconds to execute. But if I execute the Select it executes directly -
it takes only around 30 ms. Why so big difference? What should I check?
I must also say, that this started this afternoon.

PG:  8.3.3
OS:  Windows Server 2003

Example below:
//========================================================================================================
CREATE OR REPLACE FUNCTION fnk_grupes_prekes(prm_pardavimo_taskas
integer, prm_grupe integer, prm_filtras character varying)
  RETURNS SETOF frt_grupes_prekes AS
$BODY$SELECT DISTINCT prek_id, prek_pavadinimas, ks_kaina, mvnt_trumpinys
FROM  filter_b_preke_matoma()
 LEFT OUTER JOIN b_grupes_prekes ON (gp_preke=prek_id)
 LEFT OUTER JOIN b_grupe ON (gp_grupe=grup_id)
 JOIN b_mato_vienetai ON (mvnt_id=prek_matovnt)
 JOIN b_kainorascio_sudetis ON (ks_preke = prek_id)
 JOIN b_kainorascio_grafikas ON (ks_kainorastis=kag_kainorastis)
 JOIN b_pardavimo_tasko_kainorastis ON (ks_kainorastis=ptk_kainorastis)
WHERE (grup_id=$2 OR $2 is Null)
  AND ptk_pardavimotaskas=$1
  AND ((prek_pavadinimas ILIKE ('%'||$3||'%')) OR $3 is NULL)
  AND fnk_grafikas_galioja(kag_grafikas) = true
ORDER BY prek_pavadinimas
$BODY$
  LANGUAGE 'sql' VOLATILE
  COST 100
  ROWS 1000;
ALTER FUNCTION fnk_grupes_prekes(integer, integer, character varying)
OWNER TO postgres;
GRANT EXECUTE ON FUNCTION fnk_grupes_prekes(integer, integer, character
varying) TO postgres;
GRANT EXECUTE ON FUNCTION fnk_grupes_prekes(integer, integer, character
varying) TO public;


select  *  from fnk_grupes_prekes(18,42,NULL);
Total query runtime: 2172 ms.
0 rows retrieved.


SELECT DISTINCT prek_id, prek_pavadinimas, ks_kaina, mvnt_trumpinys
FROM  filter_b_preke_matoma()
 LEFT OUTER JOIN b_grupes_prekes ON (gp_preke=prek_id)
 LEFT OUTER JOIN b_grupe ON (gp_grupe=grup_id)
 JOIN b_mato_vienetai ON (mvnt_id=prek_matovnt)
 JOIN b_kainorascio_sudetis ON (ks_preke = prek_id)
 JOIN b_kainorascio_grafikas ON (ks_kainorastis=kag_kainorastis)
 JOIN b_pardavimo_tasko_kainorastis ON (ks_kainorastis=ptk_kainorastis)
WHERE (grup_id=42 OR 42 is Null)
  AND ptk_pardavimotaskas=18
  AND ((prek_pavadinimas ILIKE ('%'||null||'%')) OR null is NULL)
  AND fnk_grafikas_galioja(kag_grafikas) = true
ORDER BY prek_pavadinimas;

Total query runtime: 47 ms.
0 rows retrieved.

--

Julius Tuskenis
Programavimo skyriaus vadovas
UAB nSoft
mob. +37068233050