Re: Optimizing query

From: pasman pasmański <pasman(dot)p(at)gmail(dot)com>
To: pgsql-performance(at)postgresql(dot)org
Subject: Re: Optimizing query
Date: 2010-11-26 15:06:18
Message-ID: AANLkTikG=Y-nZSOfUebswbhxMvS4Y+BEk7arxmu4dyqU@mail.gmail.com
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Thanks for reply.

First query:

SELECT
R."Osoba weryfikująca" AS "Osoba",
R."LP"::text AS "Sprawa",
A."NKA",
A."NTA",
Sum(A."Ile")::text AS "Ilość CDR"
FROM
ONLY "NumeryA" A
LEFT JOIN
"Rejestr stacji do naprawy" R
ON
A."NKA" = R."Numer kierunkowy"
and A."NTA" like R."Numer stacji"
and substr(A."NTA",1,5) = substr(R."Numer stacji",1,5)

WHERE
"DataPliku" >= current_date-4*30
and "KodBłędu"=74::text
and "Data weryfikacji" >= current_date-4*30

GROUP BY R."Osoba weryfikująca",R."LP",A."NKA", A."NTA"
ORDER BY Sum("Ile") DESC
LIMIT 5000

-----------------------
Explain analyze
-----------------------

"Limit (cost=8806.28..8806.30 rows=5 width=28) (actual
time=2575.143..2607.092 rows=5000 loops=1)"
" -> Sort (cost=8806.28..8806.30 rows=5 width=28) (actual
time=2575.135..2586.797 rows=5000 loops=1)"
" Sort Key: (sum(a."Ile"))"
" Sort Method: quicksort Memory: 929kB"
" -> HashAggregate (cost=8806.12..8806.23 rows=5 width=28)
(actual time=2500.549..2544.315 rows=9564 loops=1)"
" -> Merge Join (cost=8196.81..8806.04 rows=5 width=28)
(actual time=1583.222..2368.858 rows=37364 loops=1)"
" Merge Cond: (((a."NKA")::text = (r."Numer
kierunkowy")::text) AND ((substr((a."NTA")::text, 1, 5)) =
(substr((r."Numer stacji")::text, 1, 5))))"
" Join Filter: ((a."NTA")::text ~~ (r."Numer stacji")::text)"
" -> Sort (cost=5883.01..5952.95 rows=27977
width=15) (actual time=1006.220..1118.692 rows=46769 loops=1)"
" Sort Key: a."NKA", (substr((a."NTA")::text, 1, 5))"
" Sort Method: quicksort Memory: 4313kB"
" -> Bitmap Heap Scan on "NumeryA" a
(cost=1454.33..3816.64 rows=27977 width=15) (actual
time=16.331..158.007 rows=46769 loops=1)"
" Recheck Cond: (("DataPliku" >=
(('now'::text)::date - 120)) AND (("KodBłędu")::text = '74'::text))"
" -> Bitmap Index Scan on dp_kb
(cost=0.00..1447.34 rows=27977 width=0) (actual time=15.838..15.838
rows=46769 loops=1)"
" Index Cond: (("DataPliku" >=
(('now'::text)::date - 120)) AND (("KodBłędu")::text = '74'::text))"
" -> Sort (cost=2313.79..2364.81 rows=20410
width=24) (actual time=576.966..703.179 rows=56866 loops=1)"
" Sort Key: r."Numer kierunkowy",
(substr((r."Numer stacji")::text, 1, 5))"
" Sort Method: quicksort Memory: 1973kB"
" -> Seq Scan on "Rejestr stacji do naprawy"
r (cost=0.00..852.74 rows=20410 width=24) (actual time=0.050..143.901
rows=20768 loops=1)"
" Filter: ("Data weryfikacji" >=
(('now'::text)::date - 120))"
"Total runtime: 2620.220 ms"

---------------------------
Second query:
----------------------------
SELECT
A."NKA",
A."NTA",
Sum("Ile") AS ss -- if it's in this table
FROM "NumeryA" A
WHERE
A."DataPliku" >= current_date-4*30
and A."KodBłędu"=74::text
GROUP BY A."NKA", A."NTA"

--------------------------------
Explain analyze:
--------------------------------

"HashAggregate (cost=20616.64..20643.22 rows=2798 width=15) (actual
time=13244.712..13284.490 rows=14288 loops=1)"
" -> Append (cost=1454.33..20406.79 rows=27979 width=15) (actual
time=16.811..13093.395 rows=46769 loops=1)"
" -> Bitmap Heap Scan on "NumeryA" a (cost=1454.33..3816.64
rows=27977 width=15) (actual time=16.804..141.495 rows=46769 loops=1)"
" Recheck Cond: (("DataPliku" >= (('now'::text)::date -
120)) AND (("KodBłędu")::text = '74'::text))"
" -> Bitmap Index Scan on dp_kb (cost=0.00..1447.34
rows=27977 width=0) (actual time=16.289..16.289 rows=46769 loops=1)"
" Index Cond: (("DataPliku" >= (('now'::text)::date
- 120)) AND (("KodBłędu")::text = '74'::text))"
" -> Seq Scan on "NumeryA_2008" a (cost=0.00..16590.16 rows=2
width=15) (actual time=12759.731..12759.731 rows=0 loops=1)"
" Filter: ((("KodBłędu")::text = '74'::text) AND
("DataPliku" >= (('now'::text)::date - 120)))"
"Total runtime: 13314.149 ms"

The first query looks to work faster than original (6s) thanks !!! :)

------------
pasman

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