Re: enhance wraparound warnings

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