From: Tom Lane <tgl@sss.pgh.pa.us>
To: Michael Lewis <mlewis@entrata.com>
cc: kimaidou <kimaidou@gmail.com>, Justin Pryzby <pryzby@telsasoft.com>,
        postgres performance list <pgsql-performance@postgresql.org>
Subject: Re: Aggregate and many LEFT JOIN
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Comments: In-reply-to Michael Lewis <mlewis@entrata.com>
	message dated "Fri, 22 Feb 2019 10:18:02 -0700"
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Date: Fri, 22 Feb 2019 13:05:59 -0500
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Michael Lewis <mlewis@entrata.com> writes:
> Does the plan change significantly with this-
> set session work_mem='250MB';
> set session geqo_threshold = 20;
> set session join_collapse_limit = 20;

Yeah ... by my count there are 16 tables in this query, so raising
join_collapse_limit to 15 is not enough to ensure that the planner
considers all join orders.  Whether use of GEQO is a big problem
is harder to say, but it might be.

			regards, tom lane