Re: Support logical replication of DDLs - Mailing list pgsql-hackers

On Thu, Mar 28, 2024 at 5:31 PM Andrey M. Borodin <x4mmm@yandex-team.ru> wrote:
>
> This thread is registered on CF [0] but is not active since 2023. Is anyone working on this? I understand that this is a nice feature. Should we move it to next CF or withdraw CF entry?
>

At this stage, we should close either Returned With Feedback or
Withdrawn as this requires a lot of work.

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With Regards,
Amit Kapila.

Hello there,
I'm interested in logical DDL replication and I've read through this thread, which has provided me with a lot of valuable information. However, I have a couple of questions that I hope, you could help me with:
1) It seems that a lot of the work done here is simply to extend the existing functionality to work with JSONB. From a development point of view, it seems appropriate to separate this into a new discussion and commit, just to expand the functionality of JSONB in terms of use for development inside the postgres.
2) inside the timeline, it seems that work is moving towards creating an MVP, which can then be finalized. As a result, it seems that the most recent fixes, especially those related to table replication, have been completed, or at least are not discussed in this section. The discussion ends suddenly, so I don't quite understand: are we facing some unsolvable problems, or we just didn't have enough time and energy to bring this to an end?
3) Unfortunately, I couldn't find any specific tests specifically for ddl logical replication. It seems logical to me that covering all possible cases of ddl replication with tests will help move the work forward and convince possible skeptics about worked issues. Did I miss this work or were they just not implemented for some other reason?
4) We decided to use event trigger and logical_message instead of extending the standard logical replication functionality by iterating through WAL records in walsender and decoding there. Was there any reason why we didn't even consider the possibility of doing everything within the structure of the existing logical replication architecture, simply extending it to work with ddl?
5) As for event triggers, I am confused by its use in terms of security and fault tolerance. After reviewing the source code of event triggers, I did not find any problems, but it seems strange that this technology is not used inside Postgres. Perhaps there are reasons for this, or is it such a good technology that it has no problems (or did I just skip this discussion)?