Re: pg_upgrade resets timeline to 1

On Thu, May 28, 2015 at 10:20:58AM -0400, Bruce Momjian wrote:
> On Thu, May 28, 2015 at 08:47:07AM +0100, Simon Riggs wrote:
> > What we should be saying is that the last timeline doesn't need a history file.
> > Then no change is needed here.
>
> Yes, that would make a lot more sense than what we have now, but this
> had to be backpatched, so reverting to the 9.3 and earlier behavior
> seemed logical.

To clarify for the archives, the 2015-05-16 changes did not revert to 9.3 and
earlier behavior. Rather, they standardized on the {9.0,9.1,9.2}-to-{9.3,9.4}
upgrade behavior, bringing that behavior to all supported branches and source
versions. Here is the history of timeline restoration in pg_upgrade:

On Thu, May 28, 2015 at 03:27:21AM -0400, Noah Misch wrote:
> Since the 2015-05-16 commits you cite, pg_upgrade always sets TLI=1. Behavior
> before those commits depended on the source and destination major versions.
> PostgreSQL 9.0, 9.1 and 9.2 restored the TLI regardless of source version.
> PostgreSQL 9.3 and 9.4 restored the TLI when upgrading from 9.3 or 9.4, but
> they set TLI=1 when upgrading from 9.2 or earlier. (Commit 038f3a0 introduced
> this inconsistent behavior of 9.3 and later.)