Date: Wed, 25 May 2022 21:25:53 -0500
From: Justin Pryzby <pryzby@telsasoft.com>
To: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Cc: michael@paquier.xyz, andres@anarazel.de, nathandbossart@gmail.com,
	pgsql-hackers@postgresql.org
Subject: Re: fix stats_fetch_consistency value in postgresql.conf.sample
Message-ID: <20220526022553.GV19626@telsasoft.com>
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On Thu, May 26, 2022 at 11:10:18AM +0900, Kyotaro Horiguchi wrote:
> Yeah, "boot_val" is appropreate here.  And I noticed that pg_settings
> has the "unit" field.  I'll try using them.

I wrote this in guc.sql, which seems promising, but it needs to be rewritten in
check_guc.pl to access postgresql.conf from the source tree.  Do you want to
handle that ?

+\getenv abs_srcdir PG_ABS_SRCDIR
+\set filename :abs_srcdir '../../../../src/backend/utils/misc/postgresql.conf.sample'
+
+begin;
+CREATE TEMP TABLE sample_conf AS
+-- SELECT m[1] AS name, trim(BOTH '''' FROM m[3]) AS sample_value
+SELECT m[1] AS name, COALESCE(m[3], m[5]) AS sample_value
+FROM (SELECT regexp_split_to_table(pg_read_file(:'filename'), '\n') AS ln) conf,
+-- regexp_match(ln, '^#?([_[:alpha:]]+) (= ([^[:space:]]*)|[^ ]*$).*') AS m
+regexp_match(ln, '^#?([_[:alpha:]]+) (= ''([^'']*)''|(= ([^[:space:]]*))|[^ ]*$).*') AS m
+WHERE ln ~ '^#?[[:alpha:]]';
+
+-- test that GUCs in postgresql.conf have correct default values
+SELECT name, tsf.cooked_value, sc.sample_value
+FROM tab_settings_flags tsf JOIN sample_conf sc USING(name)
+WHERE NOT not_in_sample AND tsf.cooked_value != sc.sample_value AND tsf.cooked_value||'.0' != sc.sample_value
+ORDER BY 1;
+rollback;

It detects the original problem:

 stats_fetch_consistency     | cache                                                                    | none

And I think these should be updated it postgresql.conf to use the same unit as
in current_setting().

 track_activity_query_size   | 1kB                                                                      | 1024
 wal_buffers                 | 4MB                                                                      | -1
 wal_receiver_timeout        | 1min                                                                     | 60s
 wal_sender_timeout          | 1min                                                                     | 60s

-- 
Justin