> On 10 Sep 2026, at 23:35, Robert Haas <[email protected]> wrote: > > On Thu, Sep 10, 2026 at 5:08 PM Daniel Gustafsson <[email protected]> wrote: >> I have a feeling this had been brought up in one of all the postcommit >> threads, >> but I fail to find it now (perhaps it was a basebackup and not checksums >> thread?). The gist of that discussion was that there is somewhere between >> very >> little add nothing we can do to protect against orphaned/external files in >> the >> datadir when using the catalog as the main source of truth for what we expect >> it to contain. I wonder if the best we can do is to document exactly how to >> verify the state of the page when getting a backup page verification failure? > > I think that it is fine to disclaim external files -- if you add > random files to the data directory, stuff may break, and that's sad, > but oh well. But I think orphaned files are a completely different > ball game. That's just a normal outcome of running PostgreSQL for a > period of time under real-world conditions, and to my knowledge this > would be the first feature that doesn't work with them. I'd like to > hear what others think, but my first reaction is to think that's > probably not OK. If we don't remove the files automatically, and don't > even provide any tools to remove the files manually, I think it > follows logically that everything we ship has to cope with their > possible existence. Otherwise, it seems like we're shipping a feature > that sometimes doesn't work and for which we can't even provide > reliable steps to fix it when it doesn't.
It is too close to midnight for investigation, so I am mostly asking an open question as a TODO marker for myself in the morning: Are we guaranteed that a create relation that crash will end up with orphan files containing correct checksums? That is, if you have a cluster initdb'd with checksums on, and never use neither online checksums or pg_checksums, can you end with an orphan file from CREATE TABLE crashing which cause a backup page verification failure? -- Daniel Gustafsson
