Hi, I'm trying to figure out how to shorten a chain of logically
replicating servers. Right now we have three servers replicating like
so:
A --> B --> C
And I'd like to remove B from the chain of replication so that I only have:
A --> C
Of course, doing this without losing data is the goal. If the
replication to C breaks temporarily, that's fine, so long as all the
changes on A make it to C eventually.
I'm not sure how to proceed with this. My best theory is:
1. In a transaction, DISABLE the replication from A to B and start a
new PUBLICATION on A that C will subscribe to in step ③ below. The
hope is that this will simultaneously stop sending changes to B while
starting a log of new changes that can later be sent to C.
2. Let any changes queued on B flush to C. (How to know when they're
all flushed?)
3. Subscribe C to the new PUBLICATION created in step ①. Create the
subscription with copy_data=False. This should send all changes to C
that hadn't been sent to B, without sending the complete tables.
4. DROP all replication to/from B (this is just cleanup; the incoming
changes to B were disabled in step ①, and outgoing changes from B were
flushed in step ②).
Does this sound even close to the right approach? Logical replication
can be a bit finicky, so I'd love to have some validation of the
general approach before I go down this road.
Thanks everybody and happy new year,
Mike