RE: Added schema level support for publication. - Mailing list pgsql-hackers

On Friday, July 16, 2021 6:10 PM vignesh C <vignesh21@gmail.com>
> On Wed, Jul 14, 2021 at 6:25 PM houzj.fnst@fujitsu.com
> <houzj.fnst@fujitsu.com> wrote:
> >
> > Wednesday, July 14, 2021 6:17 PM vignesh C <vignesh21@gmail.com> wrote:
> > > On Tue, Jul 13, 2021 at 12:06 PM tanghy.fnst@fujitsu.com
> > > <tanghy.fnst@fujitsu.com> wrote:
> > > >
> > > > On Monday, July 12, 2021 5:36 PM vignesh C <vignesh21@gmail.com>
> wrote:
> > > > >
> > > > > Thanks for reporting this issue, this issue is fixed in the v10
> > > > > patch attached at [1].
> > > > > [1] - https://www.postgresql.org/message-id/CALDaNm2%2BtR%2B8R-
> > > > > sD1CSyMbZcZbkintZE-avefjsp7LCkm6HMmw%40mail.gmail.com
> > > >
> > > > Thanks for fixing it.
> > > >
> > > > By applying your V10 patch, I saw three problems, please have a look.
> > > >
> > > > 1. An issue about pg_dump.
> > > > When public schema was published, the publication was created in the
> > > > output file, but public schema was not added to it. (Other schemas
> > > > could be added as expected.)
> > > >
> > > > I looked into it and found that selectDumpableNamespace function marks
> > > DUMP_COMPONENT_DEFINITION as needless when the schema is public,
> > > leading to schema public is ignored in getPublicationSchemas. So we'd better
> > > check whether schemas should be dumped in another way.
> > > >
> > > > I tried to fix it with the following change, please have a look.
> > > > (Maybe we also need to add some comments for it.)
> > > >
> > > > diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c
> > > > index f6b4f12648..a327d2568b 100644
> > > > --- a/src/bin/pg_dump/pg_dump.c
> > > > +++ b/src/bin/pg_dump/pg_dump.c
> > > > @@ -4206,7 +4206,8 @@ getPublicationSchemas(Archive *fout,
> > > NamespaceInfo nspinfo[], int numSchemas)
> > > >                  * Ignore publication membership of schemas whose
> > > definitions are not
> > > >                  * to be dumped.
> > > >                  */
> > > > -               if (!(nsinfo->dobj.dump &
> > > DUMP_COMPONENT_DEFINITION))
> > > > +               if (!((nsinfo->dobj.dump &
> > > DUMP_COMPONENT_DEFINITION)
> > > > +                       || (strcmp(nsinfo->dobj.name, "public") == 0
> > > > + && nsinfo->dobj.dump != DUMP_COMPONENT_NONE)))
> > > >                         continue;
> > > >
> > > >                 pg_log_info("reading publication membership for schema
> > > > \"%s\"",
> > >
> > > I felt it is intentionally done like that as the pubic schema is created by default,
> > > hence it is not required to dump else we will get errors while restoring.
> > > Thougths?
> >
> > Thanks for the new patches and I also looked at this issue.
> >
> > For user defined schema and publication:
> > --------------------------
> > create schema s1;
> > create publication pub2 for SCHEMA s1;
> > --------------------------
> >
> > pg_dump will only generate the following SQLs:
> >
> > ------pg_dump result------
> > CREATE PUBLICATION pub2 WITH (publish = 'insert, update, delete, truncate');
> > ALTER PUBLICATION pub2 ADD SCHEMA s1;
> > --------------------------
> >
> > But for the public schema:
> > --------------------------
> > create publication pub for SCHEMA public;
> > --------------------------
> >
> > pg_dump will only generate the following SQL:
> >
> > ------pg_dump result------
> > CREATE PUBLICATION pub WITH (publish = 'insert, update, delete, truncate');
> > --------------------------
> >
> > It didn't generate SQL like "ALTER PUBLICATION pub ADD SCHEMA public;" which
> > means the public schema won't be published after restoring. So, I think we'd
> > better let the pg_dump generate the ADD SCHEMA public SQL. Thoughts ?
> 
> Thanks for reporting this issue, this issue is fixed in the v12 patch attached.
> 

I tested your v12 patch and found a problem in the following case.

Step 1:
postgres=# create schema s1;
CREATE SCHEMA
postgres=# create table s1.t1 (a int);
CREATE TABLE
postgres=# create publication pub_t for table s1.t1;
CREATE PUBLICATION
postgres=# create publication pub_s for schema s1;
CREATE PUBLICATION

Step 2:
pg_dump -N s1

I dumped and excluded schema s1, pg_dump generated the following SQL:
-------------------------------
ALTER PUBLICATION pub_s ADD SCHEMA s1;

I think it was not expected because SQL like "ALTER PUBLICATION pub_t ADD TABLE s1.t1" was not generated in my case.
Thoughts?

Regards
Tang