Re: Better HINT message for "unexpected data beyond EOF"

Hi,

On 2025-04-01 09:49:12 -0400, Robert Haas wrote:
> On Tue, Apr 1, 2025 at 7:13 AM Jakub Wartak
> <jakub(dot)wartak(at)enterprisedb(dot)com> wrote:
> > Thread bump. So we have the following candidates:
> >
> > 1. remove it as Andres stated:
> > ERROR: unexpected data beyond EOF in block 1472 of relation base/5/16387
> >
> > 2a. Robert's idea
> > ERROR: unexpected data beyond EOF in block 1472 of relation base/5/16387
> > HINT: This has been observed with PostgreSQL files being overwritten.
> >
> > 2b. Christoph's idea
> > ERROR: unexpected data beyond EOF in block 1472 of relation base/5/16387
> > HINT: Did anything besides PostgreSQL touch that file?

FWIW, I think these are all just about equally wrong.
1) doesn't allow the use to understand what could be the culprit
2*) omit that zero_damaged_pages can cause this due to the logic in mdreadv()

> > Another question is should we back-patch this? I believe we should (?)
>
> I don't think this qualifies as a bug. The current wording isn't
> factually wrong, just unhelpful. Even if it were wrong, we need a
> pretty good reason to change message strings in a stable branch,
> because that can break things for users who are grepping for the
> current string (or a translation thereof). If an overwhelming
> consensus in favor of back-patching emerges, fine, but my gut feeling
> is that back-patching will make more people sad than it makes happy.

I'd certainly not backpatch.

Greetings,

Andres Freund