Re: Local replication "slot does not exist" after initial sync

Sorry, two more little things here. The publisher logs add much, but here's
what we see:

STATEMENT: START_REPLICATION SLOT "pg_20031_sync_17418_7324846428853951375"
LOGICAL F1D0/346C6508 (proto_version '2', publication_names
'"compass_publication2"')
ERROR: replication slot "pg_20031_sync_17402_7324846428853951375" does not
exist

And I thought that maybe there'd be some magic in the REFRESH command on
the subscriber, so I tried that:

alter subscription xyz refresh publication;

To nobody's surprise, that didn't help. :)

On Sun, Feb 25, 2024 at 10:00 AM Mike Lissner <
mlissner(at)michaeljaylissner(dot)com> wrote:

> Hi, I set up logical replication a few days ago, but it's throwing some
> weird log lines that have me worried. Does anybody have experience with
> lines like the following on a subscriber:
>
> LOG: logical replication table synchronization worker for subscription
> "compass_subscription", table "search_opinionscitedbyrecapdocument" has
> started
> ERROR: could not start WAL streaming: ERROR: replication slot
> "pg_20031_sync_17418_7324846428853951375" does not exist
> LOG: background worker "logical replication worker" (PID 1014) exited with
> exit code 1
>
> Slots with this kind of name (pg_xyz_sync_*) are created during the
> initial sync, but it seems like the subscription is working based on a
> quick look in a few tables.
>
> I thought this might be related to running out of slots on the publisher,
> so I increased both max_replication_slots and max_wal_senders to 50 and
> rebooted so those would take effect. No luck.
>
> I thought rebooting the subscriber might help. No luck.
>
> When I look in the publisher to see the slots we have...
>
> SELECT * FROM pg_replication_slots;
>
> ...I do not see the one that's missing according to the log lines.
>
> So it seems like the initial sync might have worked properly (tables have
> content), but that I have an errant process on the subscriber that might be
> stuck in a retry loop.
>
> I haven't been able to fix this, and I think my last attempt might be a
> new subscription with copy_data=false, but I'd rather avoid that if I can.
>
> Is there a way to fix or understand this so that I don't get the log lines
> forever and so that I can be confident the replication is in good shape?
>
> Thank you!
>
>
> Mike
>