Re: Initial insert - Mailing list pgsql-performance

Hi, 

I'm trying to create datas on an initial import and i'm encountering a performance issue.

I've 2 tables, my process create a record in each table and execute a sum with join on this 2 tables. (and other requests but there are very fast)

My 2 tables are empty before the import.

My count query is :

select sum(quantitest0_.quantite_valeur) as col_0_0_ from dm5_quantitestock quantitest0_, dm5_caracteristiquearticlestock caracteris1_ where quantitest0_.id_caracteristiquearticlestock=caracteris1_.id and caracteris1_.id_article='4028804c4a311178014a346546967c59'

i use parameterized request.

My process create only 6000 records in each table.

During the whole process this sum request lasts longer and longer.

The auto-explain plan show an seq scan 

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  Query Text: select sum(quantitest0_.quantite_valeur) as col_0_0_ from dm5_quantitestock quantitest0_, dm5_caracteristiquearticlestock caracteris1_ where quantitest0_.id_caracteristiquearticlestock=caracteris1_.id and caracteris1_.id_article=$1

        Aggregate  (cost=2.04..2.05 rows=1 width=26) (actual time=862.621..862.621 rows=1 loops=1)

          Output: sum(quantitest0_.quantite_valeur)

          ->  Nested Loop  (cost=0.00..2.04 rows=1 width=26) (actual time=862.618..862.618 rows=0 loops=1)

                Output: quantitest0_.quantite_valeur

                Join Filter: ((quantitest0_.id_caracteristiquearticlestock)::text = (caracteris1_.id)::text)

                Rows Removed by Join Filter: 1869

                ->  Seq Scan on public.dm5_quantitestock quantitest0_  (cost=0.00..1.01 rows=1 width=164) (actual time=0.004..0.408 rows=1869 loops=1)

                      Output: quantitest0_.id, quantitest0_.datefinvalidite, quantitest0_.quantite_valeur, quantitest0_.id_caracteristiquearticlestock, quantitest0_.id_caracteristiquelieustock, quantitest0_.datecreationsysteme, quantitest0_.datemodificationsysteme, quantitest0_.id_creeparsysteme, quantitest0_.id_modifieparsysteme

                ->  Seq Scan on public.dm5_caracteristiquearticlestock caracteris1_  (cost=0.00..1.01 rows=1 width=42) (actual time=0.456..0.456 rows=1 loops=1869)

                      Output: caracteris1_.id, caracteris1_.datefinvalidite, caracteris1_.id_lot, caracteris1_.id_article, caracteris1_.id_numeroserie, caracteris1_.datecreationsysteme, caracteris1_.datemodificationsysteme, caracteris1_.id_modifieparsysteme, caracteris1_.id_creeparsysteme

                      Filter: ((caracteris1_.id_article)::text = ($1)::text)

                      Rows Removed by Filter: 1869

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if a launch an analyse during the process, the explain use index, but the time remains the same.

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Query Text: select sum(quantitest0_.quantite_valeur) as col_0_0_ from dm5_quantitestock quantitest0_, dm5_caracteristiquearticlestock caracteris1_ where quantitest0_.id_caracteristiquearticlestock=caracteris1_.id and caracteris1_.id_article=$1

Aggregate  (cost=16.55..16.56 rows=1 width=26) (actual time=654.998..654.998 rows=1 loops=1)

 Output: sum(quantitest0_.quantite_valeur)

 ->  Nested Loop  (cost=0.00..16.55 rows=1 width=26) (actual time=654.994..654.994 rows=0 loops=1)

       Output: quantitest0_.quantite_valeur

       Join Filter: ((quantitest0_.id_caracteristiquearticlestock)::text = (caracteris1_.id)::text)

       Rows Removed by Join Filter: 1651

       ->  Index Scan using x_dm5_quantitestock_00 on public.dm5_quantitestock quantitest0_  (cost=0.00..8.27 rows=1 width=164) (actual time=0.011..0.579 rows=1651 loops=1)

             Output: quantitest0_.id, quantitest0_.datefinvalidite, quantitest0_.quantite_valeur, quantitest0_.id_caracteristiquearticlestock, quantitest0_.id_caracteristiquelieustock, quantitest0_.datecreationsysteme, quantitest0_.datemodificationsysteme, quantitest0_.id_creeparsysteme, quantitest0_.id_modifieparsysteme

       ->  Index Scan using dm5_caracteristiquearticlestock_pkey on public.dm5_caracteristiquearticlestock caracteris1_  (cost=0.00..8.27 rows=1 width=42) (actual time=0.395..0.395 rows=1 loops=1651)

             Output: caracteris1_.id, caracteris1_.datefinvalidite, caracteris1_.id_lot, caracteris1_.id_article, caracteris1_.id_numeroserie, caracteris1_.datecreationsysteme, caracteris1_.datemodificationsysteme, caracteris1_.id_modifieparsysteme, caracteris1_.id_creeparsysteme

             Filter: ((caracteris1_.id_article)::text = '4028804c4a311178014a346547307cce'::text)

             Rows Removed by Filter: 1651

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If i create the first 1000 records, commit and end transaction, the whole import is very fast.

I can't change my process to cut the process in little part...

An idea ? 

Thanks.

Laurent CATHALA
Architecte
[email protected]

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