Re: Support logical replication of DDLs

Amit Kapila <amit.kapila16@gmail.com>

From: Amit Kapila <amit.kapila16@gmail.com>

To: Masahiko Sawada <sawada.mshk@gmail.com>

Cc: "Zhijie Hou (Fujitsu)" <houzj.fnst@fujitsu.com>, shveta malik <shveta.malik@gmail.com>, vignesh C <vignesh21@gmail.com>, Ajin Cherian <itsajin@gmail.com>, "Wei Wang (Fujitsu)" <wangw.fnst@fujitsu.com>, Runqi Tian <runqidev@gmail.com>, Peter Smith <smithpb2250@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>, li jie <ggysxcq@gmail.com>, Dilip Kumar <dilipbalaut@gmail.com>, Alvaro Herrera <alvherre@alvh.no-ip.org>, Japin Li <japinli@hotmail.com>, rajesh singarapu <rajesh.rs0541@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Zheng Li <zhengli10@gmail.com>

Date: 2023-04-26T05:56:01Z

Lists: pgsql-hackers

Commits

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Add a run_as_owner option to subscriptions.
- 482675987bcd 16.0 cited
Refactor pgoutput_change().
- da324d6cd45b 16.0 cited
Print the correct aliases for DML target tables in ruleutils.
- df931e9ab35b 11.20 landed
- c8a5f1685fb7 15.3 landed
- 4efb4f0d4878 13.11 landed
- 3dd287c14fac 12.15 landed
- 393430f57544 16.0 landed
- 14345f3c6a7b 14.8 landed
Fix object identity string for transforms
- 9a312562314a 16.0 landed
Add grantable MAINTAIN privilege and pg_maintain role.
- 60684dd834a2 16.0 cited
Get rid of recursion-marker values in enum AlterTableType
- 840ff5f451cd 16.0 cited
Release cache tuple when no longer needed
- ed0fbc8e5ac9 15.0 cited
Empty search_path in logical replication apply worker and walsender.
- 11da97024abb 14.0 cited
Refactor format_type APIs to be more modular
- a26116c6cbf4 11.0 cited
Use wrappers of PG_DETOAST_DATUM_PACKED() more.
- 3a0d473192b2 10.0 cited

On Wed, Apr 26, 2023 at 10:01 AM Masahiko Sawada <sawada.mshk@gmail.com> wrote:
>
> On Tue, Apr 25, 2023 at 12:58 PM Zhijie Hou (Fujitsu)
> <houzj.fnst@fujitsu.com> wrote:
> >
> > Aport from above comments, I splitted the code related to verbose
> > mode to a separate patch. And here is the new version patch set.
> >
>
> As for DDL replication, we create event triggers to write deparsed DDL
> commands to WAL when creating a publication with the ddl option. The
> event triggers are recreated/dropped at ALTER/DROP PUBLICATION. I'm
> concerned it's possible that DDLs executed while such a publication
> not existing are not replicated. For example, imagine the following
> steps,
>
> 1. CREATE PUBLICATION test_pub ... WITH (ddl = 'table);
> 2. CREATE SUBSCRIPTION test_sub ... PUBLICATION test_pub;
> 3. ALTER SUBSCRIPTION test_sub DISABLE;
> 4. DROP PUBLICATION test_pub;
> 5. CREATE PUBLICATION test_pub ... WITH (ddl = 'table);
> 6. ALTER SUBSCRIPTION test_sub ENABLE;
>
> DDLs executed between 4 and 5 won't be replicated.
>

But we won't even send any DMLs between 4 and 5. In fact, WALSender
will give an error for those DMLs that publication doesn't exist as it
uses a historic snapshot. So, why do we expect DDLs between Drop and
Create of publication should be replicated?

-- 
With Regards,
Amit Kapila.