Re: pg_rewind: warn when checkpoint hasn't happened after promotion

On Sat, Jun 4, 2022 at 8:59 AM James Coleman <jtc331(at)gmail(dot)com> wrote:
> A quick background refresher: after promoting a standby rewinding the
> former primary requires that a checkpoint have been completed on the
> new primary after promotion. This is correctly documented. However
> pg_rewind incorrectly reports to the user that a rewind isn't
> necessary because the source and target are on the same timeline.

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.

--
Robert Haas
EDB: http://www.enterprisedb.com