Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> Is there anything intrinsic to the mechanism of operation of pg_rewind
> that requires a timeline change, or could we just rewind within the
> same timeline to an earlier LSN? In other words, maybe we could just
> remove this limitation of pg_rewind, and then perhaps it wouldn't be
> necessary to determine what the new timeline is.
That seems like a fairly bad idea. For example, if you've already
archived some WAL segments past the rewind target, there will shortly
be two versions of truth about what that part of the WAL space contains,
and your archiver will either spit up or do probably-the-wrong-thing.
regards, tom lane