Re: pgsql: Ensure that a standby is able to follow a primary on a newer tim

Hi Fujii-san,

On Thu, Jan 14, 2021 at 03:32:52AM +0000, Fujii Masao wrote:
> Ensure that a standby is able to follow a primary on a newer timeline.
>
> Commit 709d003fbd refactored WAL-reading code, but accidentally caused
> WalSndSegmentOpen() to fail to follow a timeline switch while reading from
> a historic timeline. This issue caused a standby to fail to follow a primary
> on a newer timeline when WAL archiving is enabled.

florican is telling that this test has some stability problems:
https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=florican&dt=2021-01-14%2003%3A55%3A45

Here I can see that replication keeps asking for a segment that's
already gone:
2021-01-13 23:34:52.104 EST [64611:1] LOG: started streaming WAL from
primary at 0/3000000 on timeline 1
2021-01-13 23:34:52.104 EST [64611:2] FATAL: could not receive data
from WAL stream: ERROR: requested WAL segment
000000010000000000000003 has already been removed

At quick glance, it seems to be an issue after the promotion of
primary_2 before starting standby_3.
--
Michael