Re: Logical replication from PG v13 and below to PG v14 (devel version) is not working.

On Mon, Sep 21, 2020 at 3:26 PM Ashutosh Sharma <ashu.coek88@gmail.com> wrote:
>
> commit 464824323e57dc4b397e8b05854d779908b55304
> Author: Amit Kapila <akapila@postgresql.org>
> Date:   Thu Sep 3 07:54:07 2020 +0530
>
> Above select query produces no result. When this experiment is
> performed below the mentioned git commit, it works fine.
>

I encountered the same issue. We get to see below error during table
sync phase in the subscriber server logs.

2020-09-21 16:01:45.794 IST [782428] LOG:  logical replication apply
worker for subscription "pg2pg_sub" has started
2020-09-21 16:01:45.799 IST [782428] ERROR:  could not start WAL
streaming: ERROR:  client sent proto_version=2 but we only support
protocol 1 or lower
    CONTEXT:  slot "pg2pg_sub", output plugin "pgoutput", in the
startup callback
2020-09-21 16:01:45.800 IST [781607] LOG:  background worker "logical
replication worker" (PID 782428) exited with exit code 1

>
> After spending some time looking into this issue, I observed that
> above git commit has bumped the logical replication protocol version.
> Due to this, the logical replication apply worker process is unable to
> do WAL streaming which causes it to terminate. Therefore, the data
> inserted in the publication table is not applied on the subscription
> table (i.e. no data replication happens)
>

That's because the above commit changed LOGICALREP_PROTO_VERSION_NUM
to 2 from 1.

With Regards,
Bharath Rupireddy.
EnterpriseDB: http://www.enterprisedb.com