Feedback-ID: ia2694551:Fastmail
Date: Fri, 5 Aug 2022 22:29:40 +0200
From: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Kyotaro Horiguchi <horikyota.ntt@gmail.com>, thomas.munro@gmail.com,
	boekewurm+postgres@gmail.com, pgsql-hackers@postgresql.org
Subject: Re: standby recovery fails (tablespace related) (tentative patch and
 discussion)
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On 2022-Jul-30, Tom Lane wrote:

> BTW, quite aside from stability, is it really necessary for this test to
> be so freakin' slow?  florican for instance reports
> 
> [12:54:07] t/033_replay_tsp_drops.pl ............ ok   117840 ms ( 0.01 usr  0.00 sys +  8.72 cusr  5.41 csys = 14.14 CPU)
> 
> 027 is so bloated because it runs the core regression tests YA time,
> which I'm not very happy about either; but that's no excuse for
> every new test to contribute an additional couple of minutes.

Definitely not intended.  It looks like the reason is just that the DROP
DATABASE/TABLESPACE commands are super slow, and this test does a lot of
that.  I added some instrumentation and the largest fraction of time
goes to execute this

		CREATE DATABASE dropme_db1 WITH TABLESPACE dropme_ts1;
		CREATE TABLE t (a int) TABLESPACE dropme_ts2;
		CREATE DATABASE dropme_db2 WITH TABLESPACE dropme_ts2;
		CREATE DATABASE moveme_db TABLESPACE source_ts;
		ALTER DATABASE moveme_db SET TABLESPACE target_ts;
		CREATE DATABASE newdb TEMPLATE template_db;
		ALTER DATABASE template_db IS_TEMPLATE = false;
		DROP DATABASE dropme_db1;
		DROP TABLE t;
		DROP DATABASE dropme_db2;
		DROP TABLESPACE dropme_ts2;
		DROP TABLESPACE source_ts;
		DROP DATABASE template_db;

Maybe this is overkill and we can reduce the test without damaging the
coverage.  I'll have a look during the weekend.

I'll repair the reliability problem too, separately.

-- 
Álvaro Herrera        Breisgau, Deutschland  —  https://www.EnterpriseDB.com/
"This is a foot just waiting to be shot"                (Andrew Dunstan)