Re: BUG: Former primary node might stuck when started as a standby

Hi,

> it might not go online, due to the error:
> new timeline N forked off current database system timeline M before current recovery point X/X
> [...]
> In this case, node1 wrote to it's WAL record 0/304DC68, but sent to node2
> only record 0/304DBF0, then node2, being promoted to primary, forked a next
> timeline from it, but when node1 was started as a standby, it first
> replayed 0/304DC68 from WAL, and then could not switch to the new timeline
> starting from the previous position.

Unless I'm missing something, this is just the right behavior of the system.

node1 has no way of knowing the history of node1/node2/nodeN
promotion. It sees that it has more data and/or inconsistent timeline
with another node and refuses to process further until DBA will
intervene. What else can node1 do, drop the data? That's not how
things are done in Postgres :) What if this is a very important data
and node2 was promoted mistakenly, either manually or by a buggy
script.

It's been a while since I seriously played with replication, but if
memory serves, a proper way to switch node1 to a replica mode would be
to use pg_rewind on it first.

--
Best regards,
Aleksander Alekseev