Re: Support logical replication of DDLs

On Wed, Apr 13, 2022 at 2:38 PM Dilip Kumar <dilipbalaut(at)gmail(dot)com> wrote:
>
> On Tue, Apr 12, 2022 at 4:25 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> >
> > > The *initial* DDL replication is a different problem than DDL replication. The
> > > former requires a snapshot to read the current catalog data and build a CREATE
> > > command as part of the subscription process. The subsequent DDLs in that object
> > > will be handled by a different approach that is being discussed here.
> > >
> >
> > I think they are not completely independent because of the current way
> > to do initial sync followed by replication. The initial sync and
> > replication need some mechanism to ensure that one of those doesn't
> > overwrite the work done by the other. Now, the initial idea and patch
> > can be developed separately but I think both the patches have some
> > dependency.
>
> I agree with the point that their design can not be completely
> independent. They have some logical relationship of what schema will
> be copied by the initial sync and where is the exact boundary from
> which we will start sending as replication. And suppose first we only
> plan to implement the replication part then how the user will know
> what all schema user has to create and what will be replicated using
> DDL replication? Suppose the user takes a dump and copies all the
> schema and then creates the subscription, then how we are we going to
> handle the DDL concurrent to the subscription command?
>

Right, I also don't see how it can be done in the current
implementation. So, I think even if we want to develop these two as
separate patches they need to be integrated to make the solution
complete.

--
With Regards,
Amit Kapila.