Re: pg_rewind does not rewind diverging timelines

On 6/1/26 08:30, Kyotaro Horiguchi wrote:
> Sorry, I only just noticed this thread.
>
> I may be missing something, but UUID feels somewhat heavyweight to me
> for this problem.
>
> I wonder whether strengthening the history-based matching would be
> sufficient instead. If timelines with the same TLI but different
> histories can be treated as distinct and pg_rewind continues walking
> the history chain until it finds a common ancestor, that seems like a
> fairly natural fit with the existing timeline model.

Unfortunately, I do not think that will work. For the normally
problematic case, the two competing TLIs will have the same history. I
added extra tests to support a divergence further back, but I find this
a rare case.

> UUIDs would certainly make identification straightforward, although
> they would also introduce longer identifiers that are a bit less
> convenient for humans to work with. My initial thought is that it may
> be worth exploring how far we can get with the existing history
> information before introducing a new identifier.

Well, although they are written to the file, the normal TLI is just an
extra defense, not a replacement for the TLI.

Best wishes,
Mats Kindahl