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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Eric Raskin <eraskin@paslists.com>
Cc: pgsql-performance@lists.postgresql.org
Subject: Re: Adding nextval() to a select caused hang/very slow execution
Date: Wed, 04 Nov 2020 14:35:44 -0500
Message-ID: <1238445.1604518544@sss.pgh.pa.us> (raw)
In-Reply-To: <CAF9L-R5Ff5ouhKCzrk6sjF=JCQBzDmkxBpedci3J3HC-jAvinQ@mail.gmail.com>
References: <CAF9L-R7G_ge=v21mnfH=sbfCt9LF7LhaDbUzqso+LsFhgeKbyQ@mail.gmail.com>
	<1234726.1604513058@sss.pgh.pa.us>
	<CAF9L-R4oiksGgY8AWVfpYqCnMpyPDPk8-Sct05buKmkbVM03_w@mail.gmail.com>
	<CAF9L-R4ve0h0xHO9S6EHX7tK6wpZPuy44d1O8=SqqyCxHW7z2A@mail.gmail.com>
	<1237035.1604516511@sss.pgh.pa.us>
	<CAF9L-R42+L101Pg63bUFFtXWzRqGcHLkL6DFibfqUprNccTEZw@mail.gmail.com>
	<1237916.1604517808@sss.pgh.pa.us>
	<CAF9L-R5Ff5ouhKCzrk6sjF=JCQBzDmkxBpedci3J3HC-jAvinQ@mail.gmail.com>

... btw, it occurs to me that at least as a stopgap,
"set enable_nestloop = off" would be worth trying.
The killer problem with rowcount-1 estimates is that they
encourage the planner to use nestloops when it shouldn't.

			regards, tom lane





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