Horton

Re: Support logical replication of DDLs

Masahiko Sawada <sawada.mshk@gmail.com>

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From: Masahiko Sawada <sawada.mshk@gmail.com>
To: "Zhijie Hou (Fujitsu)" <houzj.fnst@fujitsu.com>
Cc: shveta malik <shveta.malik@gmail.com>, Amit Kapila <amit.kapila16@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: 2023-04-26T04:31:17Z
Lists: pgsql-hackers

Commits

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  1. Add a run_as_owner option to subscriptions.

  2. Refactor pgoutput_change().

  3. Print the correct aliases for DML target tables in ruleutils.

  4. Fix object identity string for transforms

  5. Add grantable MAINTAIN privilege and pg_maintain role.

  6. Get rid of recursion-marker values in enum AlterTableType

  7. Release cache tuple when no longer needed

  8. Empty search_path in logical replication apply worker and walsender.

  9. Refactor format_type APIs to be more modular

  10. Use wrappers of PG_DETOAST_DATUM_PACKED() more.

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. The same is true
when we unset the ddl option instead of dropping the publication. IIUC
it seems not to be a good idea to tie the event triggers with
publications. I don't have any good alternative ideas for now, though.

Regards,

--
Masahiko Sawada
Amazon Web Services: https://aws.amazon.com