Re: Support logical replication of DDLs

On Sat, Jul 2, 2022 at 8:51 AM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>
> On Fri, Jul 1, 2022 at 10:22 PM vignesh C <vignesh21(at)gmail(dot)com> wrote:
> >
> > On Wed, Jun 29, 2022 at 3:25 PM houzj(dot)fnst(at)fujitsu(dot)com
> > <houzj(dot)fnst(at)fujitsu(dot)com> wrote:
> > >
> >
> > Thanks for the updated patch.
> > Few comments on 0002 patch:
> > 1) When we create a subscription for a publication with the existing
> > default PUBLISH parameter having default value as
> > 'insert,update,delete,truncate', we do an initial table sync to get
> > the initial table data from the publisher to the subscriber. But in
> > case of a publication created with 'ddl', the subscription expects the
> > existing initial tables present in the publisher to be created
> > beforehand in the subscriber. Should this be the default behavior?
> > Should we do a ddl dump for all the tables and restore the ddl to the
> > subscription while creating the subscription? Or is this planned as an
> > option for the later version.
> >
>
> The idea is to develop initial sync (for ddl replication) as a
> separate patch. But both need to be integrated at some point.

Yes, that approach makes sense.

> >
> > 3) SYNTAX Support:
> > Currently creation of "FOR TABLE" publication with ddl is supported.
> > Should we allow support of ddl for "FOR TABLE" publication.
> >
>
> The above comment is unclear to me. It seems to me in the first
> sentence, you are saying that the "FOR TABLE" syntax is supported and
> in the second sentence, you are asking to allow support of it? I think
> at this stage, the focus is to build the core part of the feature
> (allow ddl replication and deparsing support), and then we can discuss
> more on Syntax. Having said that, it will be good if we can support
> table-level DDL replication as well in the patch as you seem to be
> suggesting.

I initially thought that supporting "FOR TABLE" publication for ddl
might not be useful as currently the create subscription fails with
table does not exist error. Now that the initial sync for ddl
replication will also be implemented as mentioned in [1], this issue
will be handled. I agree with supporting table-level DDL replication.

[1] - https://www.postgresql.org/message-id/CAA4eK1%2B5zJAT_RYOAEOq8M33s196kR5sDyLQLUXd8Rnqr%2BiB0Q%40mail.gmail.com

Regards,
Vignesh