Re: BUG #18203: Logical Replication initial sync failure

On Sat, 18 Nov 2023 at 18:10, PG Bug reporting form
<noreply@postgresql.org> wrote:
>
> The following bug has been logged on the website:
>
> Bug reference:      18203
> Logged by:          Justin G
> Email address:      zzzzz.graf@gmail.com
> PostgreSQL version: 15.2
> Operating system:   Ubuntu 20
> Description:
>
> We’ve found an edge case that breaks logical replication.
>
> Procedure:
>
> alter system set wal_level to 'logical' ;
>
> create database source;  --pg 11
> create database destin; --pg 15
>
> create table no_col(); -- pg 11
>
> insert into no_col default values;
> insert into no_col default values;
> insert into no_col default values;
> insert into no_col default values;
> insert into no_col default values;
>
> CREATE PUBLICATION no_col_pub for table no_col;
>
> create table no_col(); --pg 15
>
> CREATE SUBSCRIPTION no_col_sub --pg15
>     CONNECTION
>         'host=<hostname/ip>
>         port=5432
>         user=<set username>
>         dbname=source
>         password=<set the password>'
>     PUBLICATION no_col_pub
>     WITH (
>         CREATE_SLOT    = TRUE,
>         ENABLED        = TRUE,
>         COPY_DATA    = TRUE
>         );
>
>
> We now have a table with 5 null rows. This is a valid table, pg_dump will
> dump it and restore it. count(*) will return 5.
>
> The dump file produced by pg_dump version 15 generates this SQL
> COPY public.no_col  FROM stdin;
>
> However, the copy command from PG 15 using logical replication includes (),
> which normally has a list of columns between the parentheses.
>
> COPY public.no_col () TO STDOUT
>
> Logical replication worker returns with the following error:
> 2023-11-17 20:40:16.141 UTC [151084] ERROR:  could not start initial
> contents copy for table "public.no_col": ERROR:  syntax error at or near
> ")"
>     LINE 1: COPY public.no_col () TO STDOUT

Thanks for reporting this issue, I was able to reproduce the issue.
This issue is happening because we are trying to specify the column
list while the table sync worker is copying data for the table.
I felt we should not specify the column list when the table has no columns.
Attached patch has the changes to handle the same.

Regards,
Vignesh