Feedback-ID: ia2694551:Fastmail
Date: Sat, 17 Jan 2026 23:02:47 +0100
From: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: Euler Taveira <euler@eulerto.com>
Cc: japin <japinli@hotmail.com>, Andres Freund <andres@anarazel.de>, 
	pgsql-hackers@lists.postgresql.org, Chao Li <li.evan.chao@gmail.com>
Subject: Re: log_min_messages per backend type
Message-ID: <202601172159.zlzebobtb7kq@alvherre.pgsql>
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On 2026-Jan-15, Euler Taveira wrote:

> +	/*
> +	 * Use a stable representation of log_min_messages. The generic level is
> +	 * always the first element and the other elements (type:level) are sorted
> +	 * by process type.
> +	 */
> +	list_sort(elemlist, string_cmp);
> +	foreach(l, elemlist)
> +	{
> +		char	   *tok = (char *) lfirst(l);
> +
> +		if (strchr(tok, ':') == NULL)
> +		{
> +			elemlist = list_delete(elemlist, tok);
> +			elemlist = lcons(tok, elemlist);
> +			break;
> +		}
> +	}

> +static int
> +string_cmp(const ListCell *a, const ListCell *b)
> +{
> +	const char *s = lfirst(a);
> +	const char *t = lfirst(b);
> +
> +	return strcmp(s, t);
> +}

I'm not opposed to this idea, but I think it should be implemented not
by sorting and then moving the first element to the top of the list, but
instead by modifying the cmp function so that the desired order is
achieved directly.  So the cmp() should return -1 if element a has no
colon, or 1 if element b has no colon, otherwise return per strcmp.
That way you can remove the foreach() block above, which is icky.

-- 
Álvaro Herrera               48°01'N 7°57'E  —  https://www.EnterpriseDB.com/
"Computing is too important to be left to men." (Karen Spärck Jones)