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Re: [PERFORM] Performance Issue -- "Materialize" - Mailing list pgsql-performance

From Carlos Augusto Machado
Subject Re: [PERFORM] Performance Issue -- "Materialize"
Date
Msg-id CAK2MEjur9Mtw+XKAO_DGBXROtLV=84PpNCpuZ7GLenZPt=2Piw@mail.gmail.com
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In response to Re: [PERFORM] Performance Issue -- "Materialize"  (Carlos Augusto Machado <caugustom@gmail.com>)
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I think you query is a bit confusing and have many subqueries, so I tried to simplify

If you cant´t have more import_num = 0 to the same login, try this

SELECT count(*)
FROM test_tab tab1
LEFT JOIN test_tab tab2
    ON tab1.login = tab2.login AND tab2.import_num = '0'
WHERE 
   tab2.login IS NULL AND
   import_num = '4520440'

otherwise try this

SELECT count(*)
FROM test_tab tab1
LEFT JOIN (
   SELECT DISTINCT login FROM test_tab WHERE import_num = '0'
) tab2
    ON tab1.login = tab2.login
WHERE 
   tab2.login IS NULL AND
   import_num = '4520440'


Em seg, 21 de ago de 2017 às 15:47, Carlos Augusto Machado <caugustom@gmail.com> escreveu:

Do you have an index on login column ?

If not, try creating an index and taking off those DISTICTs.

Em seg, 21 de ago de 2017 às 15:33, Justin Pryzby <pryzby@telsasoft.com> escreveu:
On Sat, Aug 19, 2017 at 10:37:56AM -0700, anand086 wrote:
> +-----------------------------------------------------------------------------------------------------------------------------------------------------------+|
> QUERY PLAN
> |+-----------------------------------------------------------------------------------------------------------------------------------------------------------+|
> Aggregate  (cost=351405.08..351405.09 rows=1 width=8)

Would you send explain ANALYZE and not just explain ?

Justin


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