Re: Fails to work on live images due to fsync() on pg_commit_ts before doing any write there

On Wed, Nov 8, 2017 at 4:42 PM, Raphael Hertzog <hertzog(at)debian(dot)org> wrote:
> On Wed, 08 Nov 2017, Michael Paquier wrote:
>> Raphaël, don't you have problems with pg_twophase as well? Wouldn't
>> the new fsync call in CheckPointTwoPhase() fail equally if no 2PC
>> transactions have happened in a checkpoint cycle? That would not be an
>> issue with pg_commit_ts and pg_xact normally, but we are talking about
>> checkpoints skipped or not depending on WAL activity, tracking which
>> is more properly done in v10.
>
> I don't know. It's quite possible, I have not used PostgreSQL 10
> extensively in Kali... I rely on Kali users for this.
>
> I just checked and the usual database initialization code does not trigger
> any write to pg_twophase so if there's a new fsync() on that directory
> without any prior write, it's quite possible that this could fail later
> on during PostgreSQL's use.

You can check that by using a manual CHECKPOINT query for example.
Based on what I see on this thread, my guess is that a failure would
show up.
--
Michael