From: Tom Lane <tgl@sss.pgh.pa.us>
To: Fujii Masao <masao.fujii@oss.nttdata.com>
cc: "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>,
        Andy Fan <zhihuifan1213@163.com>,
        "'Michael Paquier'" <michael@paquier.xyz>,
        PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Subject: Re: A assert failure when initdb with track_commit_timestamp=on
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Comments: In-reply-to Fujii Masao <masao.fujii@oss.nttdata.com>
	message dated "Fri, 04 Jul 2025 17:45:46 +0900"
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Date: Fri, 04 Jul 2025 11:30:17 -0400
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Fujii Masao <masao.fujii@oss.nttdata.com> writes:
> On 2025/07/04 16:29, Hayato Kuroda (Fujitsu) wrote:
>> If more GUCs were found which cannot be set during the bootstrap mode, =
how about
>> introducing a new flag like GUC_DEFAULT_WHILE_BOOTSTRAPPING for GUC var=
iables?
>> If the flag is set all setting can be ignored when
>> IsBootstrapProcessingMode() =3D true.

> If there are many GUCs that behave incorrectly during bootstrap,
> a general mechanism like that might be worth considering. But if
> only a few GUCs are affected, as I believe is the case,
> then such a mechanism may be overkill.

As I remarked in the other thread, I don't like inventing a different
solution for each GUC.  So if there are even two that need something
done, I think Hayato-san's idea has merit.

The core of the patch could be as little as

diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 667df448732..43f289924e6 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -3464,6 +3464,15 @@ set_config_with_handle(const char *name, config_han=
dle *handle,
 		return 0;
 	}
 =

+	/*
+	 * Certain GUCs aren't safe to enable during bootstrap mode.  Silently
+	 * ignore attempts to set them to non-default values.
+	 */
+	if (unlikely(IsBootstrapProcessingMode()) &&
+		(record->flags & GUC_IGNORE_IN_BOOTSTRAP) &&
+		source !=3D PGC_S_DEFAULT)
+		changeVal =3D false;
+
 	/*
 	 * Check if the option can be set at this time. See guc.h for the precis=
e
 	 * rules.

If we went this way, we'd presumably revert 5a6c39b6d in favor
of marking track_commit_timestamp with this flag.

			regards, tom lane