Re: Initial Schema Sync for Logical Replication

On Wed, Jul 5, 2023 at 7:45 AM Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
>
> On Mon, Jun 19, 2023 at 5:29 PM Peter Smith <smithpb2250(at)gmail(dot)com> wrote:
> >
> > Hi,
> >
> > Below are my review comments for the PoC patch 0001.
> >
> > In addition, the patch needed rebasing, and, after I rebased it
> > locally in my private environment there were still test failures:
> > a) The 'make check' tests fail but only in a minor way due to changes colname
> > b) the subscription TAP test did not work at all for me -- many errors.
>
> Thank you for reviewing the patch.
>
> While updating the patch, I realized that the current approach won't
> work well or at least has the problem with partition tables. If a
> publication has a partitioned table with publish_via_root = false, the
> subscriber launches tablesync workers for its partitions so that each
> tablesync worker copies data of each partition. Similarly, if it has a
> partition table with publish_via_root = true, the subscriber launches
> a tablesync worker for the parent table. With the current design,
> since the tablesync worker is responsible for both schema and data
> synchronization for the target table, it won't be possible to
> synchronize both the parent table's schema and partitions' schema.
>

I think one possibility to make this design work is that when
publish_via_root is false, then we assume that subscriber already has
parent table and then the individual tablesync workers can sync the
schema of partitions and their data. And when publish_via_root is
true, then the table sync worker is responsible to sync parent and
child tables along with data. Do you think such a mechanism can
address the partition table related cases?

--
With Regards,
Amit Kapila.