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From: Dilip Kumar <[email protected]>
To: Chao Li <[email protected]>
Cc: Amit Kapila <[email protected]>
Cc: Postgres hackers <[email protected]>
Subject: Re: Improve logical replication usability when tables lack primary keys
Date: Mon, 15 Dec 2025 08:58:20 +0530
Message-ID: <CAFiTN-ucvk8JOiLvjii6VXar6nYJvCQDgzp8_4v55yweUmzdzw@mail.gmail.com> (raw)
In-Reply-To: <[email protected]>
References: <CAEoWx2mMorbMwjKbT4YCsjDyL3r9Mp+z0bbK57VZ+OkJTgJQVQ@mail.gmail.com>
	<CAA4eK1+UL6wVDNzkpHjA7RVLD_8AkrP2tu+RvQ2h5AUjyEe+-Q@mail.gmail.com>
	<[email protected]>

On Tue, Nov 11, 2025 at 6:11 PM Chao Li <[email protected]> wrote:
>
> Hi Amit,
>
> Thanks for asking.
>
> > On Nov 11, 2025, at 19:18, Amit Kapila <[email protected]> wrote:
> >
> > On Mon, Nov 10, 2025 at 1:36 PM Chao Li <[email protected]> wrote:
> >>
> >> * BACKGROUND
> >>
> >> This requirement comes from several users operating large deployments, particularly in HIS (Hospital Information Systems). The situation can be summarized as follows:
> >>
> >> - A central DB operations team maintains the main database and configures logical replication for all tables.
> >> - Multiple third-party application vendors are allowed to create new tables in that database.
> >> - Some of these newly created tables lack a primary key. Since logical replication with `REPLICATION IDENTITY DEFAULT` requires a primary key, such tables silently fail to replicate.
> >> - The DB operations team must then spend significant effort identifying the affected tables and correcting them manually.
> >>
> >
> > Can you share an example of how we silently fail to replicate? Won't
> > in such cases UPDATE/DELETE will anyway raise an ERROR?
> >
>
> Yes, UPDATE/DELETE will fail. That’s the easy case to expose the error. Actually my patch will allow the update/delete.
>
> However, some tables, like dictionary tables, they are important, but don’t have much update/delete, they may silently fail to replicate.

But other than UPDATE/DELETE for what operation we need RI, I mean
INSERT would work without any RI and UPDATE/DELETE will fail on the
publisher itself without setting RI, so can you explain the exact case
where it will silently fail to replicate?

-- 
Regards,
Dilip Kumar
Google

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