Date: Fri, 26 Jun 2026 13:06:36 -0500
From: Nathan Bossart <nathandbossart@gmail.com>
To: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Cc: masao.fujii@gmail.com, bharath.rupireddyforpostgres@gmail.com,
	qiuwenhuifx@gmail.com, shinya11.kato@gmail.com,
	pgsql-hackers@postgresql.org
Subject: Re: enhance wraparound warnings
Message-ID: <aj6_rEJqQ1KTe_OU@nathan>
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On Fri, Jun 26, 2026 at 10:55:39AM +0900, Kyotaro Horiguchi wrote:
> I'm not sure I'm following this correctly, but the explanation above
> sounded to me as if the warning should report the number of IDs
> remaining before wraparound, e.g. "Approximately N MultiXactIds remain
> before wraparound", so I'm a bit confused by the proposed wording.

We already report the number of IDs remaining in the WARNING message.  In
v19, I've added a DETAIL message that also reports the percentage
remaining, with the hope that it makes the urgency clearer.

>> + errdetail("Approximately %.2f%% of MultiXactIds remain before wraparound.",
> 
> The attached patch adopts that wording. However, I'm not sure how to
> interpret it. The value is still expressed as a percentage, but it is
> no longer clear what that percentage is relative to.
> 
> Whichever approach we choose, I think the wording should be explicit.
> If the value is reported as a percentage, then something like "x.xx%
> of MultiXactId space remains" seems clearer to me. If it is reported
> as a count, then "N MultiXactIds remain" would make more sense.

I find both "percentage of IDs remaining" and "percentage of ID space
remaining" equally clear and have no strong opinion on the matter.

-- 
nathan