Horton

Re: Support logical replication of DDLs

Amit Kapila <amit.kapila16@gmail.com>

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From: Amit Kapila <amit.kapila16@gmail.com>
To: Zheng Li <zhengli10@gmail.com>
Cc: Peter Smith <smithpb2250@gmail.com>, vignesh C <vignesh21@gmail.com>, li jie <ggysxcq@gmail.com>, Ajin Cherian <itsajin@gmail.com>, Dilip Kumar <dilipbalaut@gmail.com>, Alvaro Herrera <alvherre@alvh.no-ip.org>, "houzj.fnst@fujitsu.com" <houzj.fnst@fujitsu.com>, Masahiko Sawada <sawada.mshk@gmail.com>, Japin Li <japinli@hotmail.com>, rajesh singarapu <rajesh.rs0541@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2023-01-19T07:05:38Z
Lists: pgsql-hackers

Commits

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  1. Add a run_as_owner option to subscriptions.

  2. Refactor pgoutput_change().

  3. Print the correct aliases for DML target tables in ruleutils.

  4. Fix object identity string for transforms

  5. Add grantable MAINTAIN privilege and pg_maintain role.

  6. Get rid of recursion-marker values in enum AlterTableType

  7. Release cache tuple when no longer needed

  8. Empty search_path in logical replication apply worker and walsender.

  9. Refactor format_type APIs to be more modular

  10. Use wrappers of PG_DETOAST_DATUM_PACKED() more.

On Thu, Jan 19, 2023 at 8:39 AM Zheng Li <zhengli10@gmail.com> wrote:
>
> On Wed, Jan 18, 2023 at 6:27 AM Amit Kapila <amit.kapila16@gmail.com> wrote:
> >
> > On Sat, Jan 7, 2023 at 8:58 PM Zheng Li <zhengli10@gmail.com> wrote:
> > >
>
> Foreign Tables can also be considered replicated with DDL replication because we
> don't even need to replicate the data as it resides on the external
> server. Users
> need to configure the external server to allow connection from the
> subscriber for
> foreign tables to work on the subscriber.
>

So, this would mean that we expect the subscriber will also have the
same foreign server as the publisher because we will replicate the
entire connection/user information of the foreign server for the
publisher. But what about data inserted by the publisher on the
foreign server?

> > We should also think
> > about initial sync for all those objects as well.
>
> Agree, we're starting an investigation on initial sync. But I think
> initial sync depends on
> DDL replication to work reliably, not the other way around. DDL replication can
> work on its own without the initial sync of schema, users just need to
> setup the initial
> schema just like they would today.
>

The difference is that today users need to take care of all schema
setup on both and follow changes in the same on the publisher. But
with DDL replication, there has to be a point prior to which both the
nodes have the same setup. For that, before setting up DDL
replication, users need to ensure that both nodes have the same
schema, and then during setup, the user doesn't perform any DDL on the
publisher.

-- 
With Regards,
Amit Kapila.