Hello. I have a query which works a bit slow. It's runned on desktop computer: AMD Athlon X2 2GHz , Win Xp sp2, 1GB ram. Postgres 8.4.5 with some changes in config: shared_buffers = 200MB # min 128kB # (change requires restart) temp_buffers = 8MB # min 800kB work_mem = 12MB # min 64kB maintenance_work_mem = 32MB # min 1MB Indexes in table "NumeryA": "NTA", "NKA", "KodBłędu", "Plik" primary key "DataPliku", "KodBłędu" index dp_kb "NKA", "NTA" index nka_nta Indexes in table "Rejestr stacji do naprawy": "LP" - primary key "Numer kierunkowy", substr("Numer stacji"::text, 1, 5) - index "3" "Data weryfikacji" - index "Data weryfikacji_1" "Numer kierunkowy", "Numer stacji", "Data odrzucania bilingu z Serat" - index "Powtórzenia" --------------------- Query is: ---------------------- SELECT A."NKA", A."NTA", Min("PołączeniaMin") || ',' || Max("PołączeniaMax") AS "Biling", Sum("Ile")::text AS "Ilość CDR", R."LP"::text AS "Sprawa", (R."Osoba weryfikująca") AS "Osoba", to_char(min("Wartość"),'FM9999990D00') AS "Wartość po kontroli", max(R."Kontrola po naprawie w Serat - CDR")::text AS "CDR po kontroli", min(A."KodBłędu")::text AS KodBłędu, Max(to_char(R."Data kontroli",'YYYY-MM-DD')) AS "Ostatnia Kontrola" , max("Skutek wprowadzenia błednej ewidencji w Serat") as "Skutek" , sum(www.a_biling_070("NRB"))::text , sum(www.a_biling_darmowy("NRB"))::text FROM (SELECT "NumeryA".* FROM ONLY "NumeryA" WHERE "DataPliku" >= current_date-4*30 and "KodBłędu"=74::text ) AS A LEFT JOIN (SELECT * FROM "Rejestr stacji do naprawy" WHERE "Data weryfikacji" >= current_date-4*30 ) AS R ON A."NKA" = R."Numer kierunkowy" and substr(A."NTA",1,5) = substr(R."Numer stacji",1,5) and A."NTA" like R."Numer stacji" GROUP BY R."Osoba weryfikująca",R."LP",A."NKA", A."NTA" ORDER BY Sum("Ile") DESC LIMIT 5000 ---------------------- Explain analyze: ---------------------- "Limit (cost=30999.84..31012.34 rows=5000 width=149) (actual time=7448.483..7480.094 rows=5000 loops=1)" " -> Sort (cost=30999.84..31073.19 rows=29341 width=149) (actual time=7448.475..7459.663 rows=5000 loops=1)" " Sort Key: (sum("NumeryA"."Ile"))" " Sort Method: top-N heapsort Memory: 1488kB" " -> GroupAggregate (cost=11093.77..29050.46 rows=29341 width=149) (actual time=4700.654..7377.762 rows=14225 loops=1)" " -> Sort (cost=11093.77..11167.12 rows=29341 width=149) (actual time=4699.587..4812.776 rows=46732 loops=1)" " Sort Key: "Rejestr stacji do naprawy"."Osoba weryfikująca", "Rejestr stacji do naprawy"."LP", "NumeryA"."NKA", "NumeryA"."NTA"" " Sort Method: quicksort Memory: 9856kB" " -> Merge Left Join (cost=8297.99..8916.58 rows=29341 width=149) (actual time=2931.449..3735.876 rows=46732 loops=1)" " Merge Cond: ((("NumeryA"."NKA")::text = ("Rejestr stacji do naprawy"."Numer kierunkowy")::text) AND ((substr(("NumeryA"."NTA")::text, 1, 5)) = (substr(("Rejestr stacji do naprawy"."Numer stacji")::text, 1, 5))))" " Join Filter: (("NumeryA"."NTA")::text ~~ ("Rejestr stacji do naprawy"."Numer stacji")::text)" " -> Sort (cost=6062.18..6135.53 rows=29341 width=95) (actual time=2131.297..2241.303 rows=46694 loops=1)" " Sort Key: "NumeryA"."NKA", (substr(("NumeryA"."NTA")::text, 1, 5))" " Sort Method: quicksort Memory: 7327kB" " -> Bitmap Heap Scan on "NumeryA" (cost=1502.09..3884.98 rows=29341 width=95) (actual time=282.570..1215.355 rows=46694 loops=1)" " Recheck Cond: (("DataPliku" >= (('now'::text)::date - 120)) AND (("KodBłędu")::text = '74'::text))" " -> Bitmap Index Scan on dp_kb (cost=0.00..1494.75 rows=29341 width=0) (actual time=281.991..281.991 rows=46694 loops=1)" " Index Cond: (("DataPliku" >= (('now'::text)::date - 120)) AND (("KodBłędu")::text = '74'::text))" " -> Sort (cost=2235.82..2285.03 rows=19684 width=64) (actual time=800.101..922.463 rows=54902 loops=1)" " Sort Key: "Rejestr stacji do naprawy"."Numer kierunkowy", (substr(("Rejestr stacji do naprawy"."Numer stacji")::text, 1, 5))" " Sort Method: quicksort Memory: 3105kB" " -> Seq Scan on "Rejestr stacji do naprawy" (cost=0.00..831.88 rows=19684 width=64) (actual time=2.118..361.463 rows=19529 loops=1)" " Filter: ("Data weryfikacji" >= (('now'::text)::date - 120))" "Total runtime: 7495.697 ms" --------------------------------- How to make it faster ? ------------ pasman -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance