subselect query time and loops problem

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От pankaj naug
Тема subselect query time and loops problem
Дата
Msg-id 20050409202154.71561.qmail@web30507.mail.mud.yahoo.com
обсуждение исходный текст
Ответы Re: subselect query time and loops problem  (Tom Lane <tgl@sss.pgh.pa.us>)
Список pgsql-sql
hi,
 
I am using this query.
 
SELECT * FROM guild_properties_buy WHERE agent IN (SELECT agent_id FROM guild_agents WHERE   address_region = 'midlands'  AND  active='on' AND status=0) AND   country = 'United Kingdom' AND   active='on' AND status='0' ORDER BY price DESC LIMIT 10 OFFSET 0
 
when i run this in my development server i get this.
 
Limit  (cost=1680331.30..1680331.31 rows=1 width=541) (actual time=3631.97..3632.00 rows=10 loops=1)
  ->  Sort  (cost=1680331.30..1680331.31 rows=1 width=541) (actual time=3631.96..3631.98 rows=11 loops=1)
        Sort Key: price
        ->  Seq Scan on guild_properties_buy  (cost=0.00..1680331.29 rows=1 width=541) (actual time=39.39..3556.80 rows=4747 loops=1)
              Filter: ((country = 'United Kingdom'::character varying) AND (active = 'on'::character varying) AND (status = 0) AND (subplan))
              SubPlan
                ->  Materialize  (cost=57.15..57.15 rows=1 widt h=4) (actual time=0.00..0.05 rows=88 loops=27235)
                      ->  Seq Scan on guild_agents  (cost=0.00..57.15 rows=1 width=4) (actual time=0.04..1.76 rows=100 loops=1)
                            Filter: ((address_region = 'midlands'::character varying) AND (active = 'on'::character varying) AND (status = 0))
Total runtime: 3633.46 msec
 
when i run this in my hosting server i get this.
 
Limit  (cost=847964.41..847964.43 rows=10 width=1036) (actual time=28265.15..28265.19 rows=10 loops=1)
  ->  Sort  (cost=847964.41..847999.30 rows=13957 width=1036) (actual time=28265.15..28265.17 rows=11 loops=1)
        Sort Key: price
        ->  Seq Scan on guild_properties_buy  (cost=0.00..832943.58 rows=13957 width=1036) (actual time=6.88..28157.11 rows=4790 loops=1)
              Filter: ((country = 'United Kingdom'::character varying) AND (active = 'on'::character varying) AND (status = 0) AND (subplan))
              SubPlan
                ->  Seq Scan on guild_agents  (cost=0.00..56.15 rows=100 width=4) (actual time=0.01..0.95 rows=87 loops=27173)
                      Filter: ((address_region = 'midlands'::character varying) AND (active = 'on'::character varying) AND (status = 0))
Total runtime: 28269.32 msec
 
when i use my script to replace sub query then both servers run fine.
 
SELECT * FROM guild_properties_buy WHERE agent IN (
56259,56397......................
) AND   country = 'United Kingdom' AND   active='on' AND status='0' ORDER BY price DESC LIMIT 10 OFFSET 0
 
Both servers have same version with same postgresql.conf. But the time taken by both the servers with subselect are way different. the loops and the query time are completely different. both servers have same indexes.
 
Any help will be greately appreciated..
 
Best Regards
Pankaj Naug
 


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