Re: [HACKERS] Re: 9.4.1 -> 9.4.2 problem: could not access status of transaction 1

Robert Haas wrote:
> On Thu, May 28, 2015 at 8:51 AM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> > [ speculation ]
>
> OK, I finally managed to reproduce this, after some off-list help from
> Steve Kehlet (the reporter), Alvaro, and Thomas Munro. Here's how to
> do it:

It's a long list of steps, but if you consider them carefully, it
becomes clear that they are natural steps that a normal production
system would go through -- essentially the only one that's really
time-critical is the decision to pg_upgrade with a version before 9.3.5.

> In the process of investigating this, we found a few other things that
> seem like they may also be bugs:
>
> - As noted upthread, replaying an older checkpoint after a newer
> checkpoint has already happened may lead to similar problems. This
> may be possible when starting from an online base backup; or when
> restarting a standby that did not perform a restartpoint when
> replaying the last checkpoint before the shutdown.

I'm going through this one now, as it's closely related and caused
issues for us.

--
Álvaro Herrera http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services