Re: Support logical replication of DDLs

On Wed, May 11, 2022 at 6:15 PM Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>
> On Wed, May 11, 2022 at 1:09 PM Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com> wrote:
> >
> > On Mon, May 9, 2022 at 6:05 PM Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org> wrote:
> > >
> > > On 2022-May-08, Dilip Kumar wrote:
> >
> > >
> > > The code in test_ddl_deparse is a pretty lame start, not nearly good
> > > enough by a thousand miles. My real intention was to have a test
> > > harness that would first run a special SQL script to install DDL
> > > capture, then run all the regular src/test/regress scripts, and then at
> > > the end ensure that all the DDL scripts were properly reproduced -- for
> > > example transmit them to another database, replay them there, and dump
> > > both databases and compare them. However, there were challenges which I
> > > no longer remember and we were unable to complete this, and we are where
> > > we are.
> >
> > I think the regression test suite improvements in these few years make
> > it easier to implement such regression tests in order to check not
> > only the existing commands but also future changes. I'll try it if no
> > one is working on it, and let us see if there are challenges.
> >
>
> I think it is a good idea to give it a try. However, one point to note
> in this regard is that if we decide to use deparsing for DDL logical
> replication then the tests for logical replication will automatically
> test all the deparsing code.

Do you mean that in tests for logical replication we run regression
tests on the publisher and check if relations are
created/altered/dropped expectedly on the subscriber? If we rely on
tests for logical replication, I think logical replication will have
to support all future DDL changes/features.

Regards,

--
Masahiko Sawada
EDB: https://www.enterprisedb.com/