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Aggregate and many LEFT JOIN - Mailing list pgsql-performance

From	kimaidou
Subject	Aggregate and many LEFT JOIN
Date	February 22, 2019 15:14:05
Msg-id	CAMKXKO6Ltz14uVgAyxy-cGSZoOQCbU5__2mjgVPv90snONZjNw@mail.gmail.com Whole thread Raw
Responses	Re: Aggregate and many LEFT JOIN
List	pgsql-performance

Hi all,

I need to optimize the following query

I use it to create a materialized view, but I think there is room for optimization.

I tried to

SET join_collapse_limit TO 15;

with to real difference.

Explain shows that the GROUP AGGREGATE and needed sort kill the performance.

Do you have any hint how to optimize this ?

Regards

Michaël

From: Gunther Schadow
Date: 21 February 2019, 15:59:44
Subject: Re: neither CPU nor IO bound, but throttled performance

From: kimaidou
Date: 22 February 2019, 15:36:33
Subject: Slow query with aggregate and many LEFT JOINS