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

From Amit Kapila
Subject Re: Support logical replication of DDLs
Date
Msg-id CAA4eK1+h-+cxqTXp0YDsErRpoNiaP8Hu4Se7DYGymuh8j9fxHQ@mail.gmail.com
Whole thread Raw
In response to Re: Support logical replication of DDLs  (Zheng Li <zhengli10@gmail.com>)
Responses Re: Support logical replication of DDLs  (Zheng Li <zhengli10@gmail.com>)
List pgsql-hackers
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.



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