out of memory

Hello,

i have a statement which ends with
  ERROR:  out of memory
  DETAIL:  Failed on request of size 639.

i tried it several times, the number after size changes but not the outcome.

could someone tell me what information you need to tell me whats wrong?

what i have so fare is:
  PostgreSQL version: 8.1.4
  Linux version 2.6.16.20-0.12-bigsmp (geeko@buildhost) (gcc version
4.1.0 (SUSE Linux)) #1 SMP Mon Jun 19 22:25:45 UTC 2006

the statement:
SELECT catalog_prefix, supplier_aid
               , stage_1.article_data_md5(
COALESCE(src.description_short     ,'')
                                         ,
COALESCE(src.description_long      ,'')
                                         , COALESCE(src.ean
       ,'')
                                         ,
COALESCE(m2.manufacturer_name    , src.manufacturer_name)
                                         ,
COALESCE(m1.manufacturer_name_old, src.manufacturer_name, '')
                                         ,
COALESCE(src.manufacturer_aid      ,'')
                                         ) AS md5
               , COALESCE(m2.manufacturer_name, src.manufacturer_name)
AS manufacturer_name
               , COALESCE(m1.manufacturer_name_old,
src.manufacturer_name) AS manufacturer_name_old
               , description_short, description_long, ean, manufacturer_aid
             FROM        quellen.article
                         src
               LEFT JOIN ( SELECT SUBSTRING(file FROM
'^([a-zA-Z0-9]*)[.].*') AS catalog_prefix
                                 , sku AS supplier_aid
                                 , manufacturer_name_old
                            FROM quellen.manufacturer_names_old
                          ) m1 USING (catalog_prefix, supplier_aid)
               LEFT JOIN data.manufacturer_mapping
                         m2 ON (
UPPER(m2.manufacturer_name_old)=UPPER(COALESCE(m1.manufacturer_name_old,src.manufacturer_name)))
             WHERE EXISTS ( SELECT 1
                              FROM stage_1.article_category_a
                              WHERE isactive IS TRUE
                                AND root_code=(SELECT
col_root_category_id FROM quellen.cataloginfo WHERE catalog_prefix =
'root')
                                AND catalog_prefix=src.catalog_prefix
AND supplier_aid=src.supplier_aid
                          )

and the explain plan:
                                                            QUERY PLAN

----------------------------------------------------------------------------------------------------------------------------------
 Merge Right Join  (cost=17894565.16..18024911.70 rows=5792735 width=496)
   Merge Cond: ("outer"."?column3?" = "inner"."?column9?")
   ->  Sort  (cost=62.33..64.83 rows=1000 width=64)
         Sort Key: upper(version.manufacturer_name_old)
         ->  Function Scan on dblink version  (cost=0.00..12.50
rows=1000 width=64)
   ->  Sort  (cost=17894502.83..17897399.20 rows=1158547 width=464)
         Sort Key:
upper(COALESCE(manufacturer_names_old.manufacturer_name_old,
src.manufacturer_name))
         ->  Merge Left Join  (cost=17752829.62..17777814.64
rows=1158547 width=464)
               Merge Cond: (("outer".supplier_aid = "inner".sku) AND
("outer".catalog_prefix = "inner"."?column4?"))
               ->  Sort  (cost=17587009.86..17589906.23 rows=1158547 width=448)
                     Sort Key: src.supplier_aid, src.catalog_prefix
                     ->  Seq Scan on article src
(cost=0.00..17470321.68 rows=1158547 width=448)
                           Filter: (subplan)
                           SubPlan
                             ->  Index Scan using
article_category_a_pkey on article_category_a  (cost=3.44..7.46 rows=1
width=0)
                                   Index Cond: ((catalog_prefix = $1)
AND (supplier_aid = $2) AND (root_code = $0))
                                   Filter: (isactive IS TRUE)
                                   InitPlan
                                     ->  Index Scan using
cataloginfo_pkey on cataloginfo  (cost=0.00..3.44 rows=1 width=5)
                                           Index Cond: (catalog_prefix
= 'root'::text)
               ->  Sort  (cost=165819.76..169160.88 rows=1336447 width=63)
                     Sort Key: manufacturer_names_old.sku,
"substring"(manufacturer_names_old.file, '^([a-zA-Z0-9]*)[.].*'::text)
                     ->  Seq Scan on manufacturer_names_old
(cost=0.00..29836.47 rows=1336447 width=63)


greetings, anita