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order by slowing down a query by 80 times - Mailing list pgsql-performance

From	Rajesh Kumar Mallah
Subject	order by slowing down a query by 80 times
Date	June 28, 2010 11:08:51
Msg-id	AANLkTim6WXLK8iJuwZbzJjCuPr9LPau1OX7vxwYDFdkN@mail.gmail.com Whole thread Raw
Responses	Re: order by slowing down a query by 80 times Re: order by slowing down a query by 80 times
List	pgsql-performance

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Dear List,

just by removing the order by co_name reduces the query time dramatically
from ~ 9 sec to 63 ms. Can anyone please help.

Regds
Rajesh Kumar Mallah.

explain analyze SELECT * from   ( SELECT a.profile_id,a.userid,a.amount,a.category_id,a.catalog_id,a.keywords,b.co_name from general.catalogs a join general.profile_master using(profile_id) where 1=1 and co_name_vec @@   to_tsquery('manufacturer') and b.co_name is not null and a.ifmain is true ) as c order by co_name
limit 25 offset 0;

Limit (cost=0.00..3659.13 rows=25 width=129) (actual time=721.075..9241.105 rows=25 loops=1)
   -> Nested Loop (cost=0.00..1215772.28 rows=8307 width=476) (actual time=721.073..9241.050 rows=25 loops=1)
         -> Nested Loop (cost=0.00..1208212.37 rows=8307 width=476) (actual time=721.052..9240.037 rows=25 loops=1)
               -> Nested Loop (cost=0.00..1204206.26 rows=6968 width=472) (actual time=721.032..9239.516 rows=25 loops=1)
                     -> Nested Loop (cost=0.00..1154549.19 rows=6968 width=471) (actual time=721.012..9236.523 rows=25 loops=1)
                           -> Index Scan using profile_master_co_name on profile_master b (cost=0.00..1125295.59 rows=6968 width=25) (actual time=0.097..9193.154 rows=2212 loops=1)
                                 Filter: ((co_name IS NOT NULL) AND ((co_name_vec)::tsvector @@ to_tsquery('manufacturer'::text)))
                           -> Index Scan using catalog_master_profile_id_fkindex on catalog_master (cost=0.00..4.19 rows=1 width=446) (actual time=0.016..0.016 rows=0 loops=2212)
                                 Index Cond: (catalog_master.profile_id = b.profile_id)
                                 Filter: ((catalog_master.hide IS FALSE) AND ((catalog_master.hosting_status)::text = 'ACTIVE'::text))
                     -> Index Scan using profile_master_profile_id_pkey on profile_master (cost=0.00..7.11 rows=1 width=9) (actual time=0.105..0.105 rows=1 loops=25)
                           Index Cond: (profile_master.profile_id = catalog_master.profile_id)
               -> Index Scan using catalog_categories_pkey_catalog_id_category_id on catalog_categories (cost=0.00..0.56 rows=1 width=8) (actual time=0.014..0.015 rows=1 loops=25)
                     Index Cond: (catalog_categories.catalog_id = catalog_master.catalog_id)
                     Filter: (catalog_categories.ifmain IS TRUE)
         -> Index Scan using web_category_master_pkey on web_category_master (cost=0.00..0.90 rows=1 width=4) (actual time=0.034..0.036 rows=1 loops=25)
               Index Cond: (web_category_master.category_id = catalog_categories.category_id)
               Filter: ((web_category_master.status)::text = 'ACTIVE'::text)
Total runtime: 9241.304 ms

explain analyze SELECT * from   ( SELECT a.profile_id,a.userid,a.amount,a.category_id,a.catalog_id,a.keywords,b.co_name from general.catalogs a join general.profile_master b using(profile_id) where 1=1 and co_name_vec @@   to_tsquery('manufacturer') and b.co_name is not null and a.ifmain is true ) as c limit 25 offset 0;
                                                                                      QUERY PLAN

----------------------------------------------------------------------------------------------
Limit (cost=0.00..358.85 rows=25 width=476) (actual time=0.680..63.176 rows=25 loops=1)
   -> Nested Loop (cost=0.00..119238.58 rows=8307 width=476) (actual time=0.677..63.139 rows=25 loops=1)
         -> Nested Loop (cost=0.00..111678.66 rows=8307 width=476) (actual time=0.649..62.789 rows=25 loops=1)
               -> Nested Loop (cost=0.00..107672.56 rows=6968 width=472) (actual time=0.626..62.436 rows=25 loops=1)
                     -> Nested Loop (cost=0.00..58015.49 rows=6968 width=471) (actual time=0.606..62.013 rows=25 loops=1)
                           -> Index Scan using profile_master_co_name_vec on profile_master b (cost=0.00..28761.89 rows=6968 width=25) (actual time=0.071..50.576 rows=1160 loops=1)
                                 Index Cond: ((co_name_vec)::tsvector @@ to_tsquery('manufacturer'::text))
                                 Filter: (co_name IS NOT NULL)
                           -> Index Scan using catalog_master_profile_id_fkindex on catalog_master (cost=0.00..4.19 rows=1 width=446) (actual time=0.008..0.008 rows=0 loops=1160)
                                 Index Cond: (catalog_master.profile_id = b.profile_id)
                                 Filter: ((catalog_master.hide IS FALSE) AND ((catalog_master.hosting_status)::text = 'ACTIVE'::text))
                     -> Index Scan using profile_master_profile_id_pkey on profile_master (cost=0.00..7.11 rows=1 width=9) (actual time=0.012..0.012 rows=1 loops=25)
                           Index Cond: (profile_master.profile_id = catalog_master.profile_id)
               -> Index Scan using catalog_categories_pkey_catalog_id_category_id on catalog_categories (cost=0.00..0.56 rows=1 width=8) (actual time=0.010..0.011 rows=1 loops=25)
                     Index Cond: (catalog_categories.catalog_id = catalog_master.catalog_id)
                     Filter: (catalog_categories.ifmain IS TRUE)
         -> Index Scan using web_category_master_pkey on web_category_master (cost=0.00..0.90 rows=1 width=4) (actual time=0.009..0.010 rows=1 loops=25)
               Index Cond: (web_category_master.category_id = catalog_categories.category_id)
               Filter: ((web_category_master.status)::text = 'ACTIVE'::text)
Total runtime: 63.378 ms

pgsql-performance by date:

From: Dimitri Fontaine
Date: 28 June 2010, 08:01:32
Subject: Re: Architecting a database

From: Yeb Havinga
Date: 28 June 2010, 11:39:10
Subject: Re: order by slowing down a query by 80 times

order by slowing down a query by 80 times - Mailing list pgsql-performance

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