Re: Support logical replication of DDLs

On Tue, Apr 25, 2023 at 12:58 PM Zhijie Hou (Fujitsu)
<houzj(dot)fnst(at)fujitsu(dot)com> wrote:
>
> Aport from above comments, I splitted the code related to verbose
> mode to a separate patch. And here is the new version patch set.
>

As for DDL replication, we create event triggers to write deparsed DDL
commands to WAL when creating a publication with the ddl option. The
event triggers are recreated/dropped at ALTER/DROP PUBLICATION. I'm
concerned it's possible that DDLs executed while such a publication
not existing are not replicated. For example, imagine the following
steps,

1. CREATE PUBLICATION test_pub ... WITH (ddl = 'table);
2. CREATE SUBSCRIPTION test_sub ... PUBLICATION test_pub;
3. ALTER SUBSCRIPTION test_sub DISABLE;
4. DROP PUBLICATION test_pub;
5. CREATE PUBLICATION test_pub ... WITH (ddl = 'table);
6. ALTER SUBSCRIPTION test_sub ENABLE;

DDLs executed between 4 and 5 won't be replicated. The same is true
when we unset the ddl option instead of dropping the publication. IIUC
it seems not to be a good idea to tie the event triggers with
publications. I don't have any good alternative ideas for now, though.

Regards,

--
Masahiko Sawada
Amazon Web Services: https://aws.amazon.com