Horton

Re: Support logical replication of DDLs

Amit Kapila <amit.kapila16@gmail.com>

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From: Amit Kapila <amit.kapila16@gmail.com>
To: Dilip Kumar <dilipbalaut@gmail.com>
Cc: Zheng Li <zhengli10@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, rajesh.rs0541@gmail.com
Date: 2022-04-08T11:00:13Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  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, Mar 29, 2022 at 9:47 AM Dilip Kumar <dilipbalaut@gmail.com> wrote:
> >
> > The idea is to force skipping any direct data population (which can
> > potentially cause data inconsistency on the subscriber)
> > in CREATE AS and SELECT INTO command on the subscriber by forcing the
> > skipData flag in the intoClause of the parsetree after
> > the logical replication worker parses the command. The data sync will
> > be taken care of by the DML replication after the DDL replication
> > finishes.
>
> Okay, something like that should work, I am not sure it is the best
> design though.
>

Even if this works, how will we make Alter Table statement work where
it needs to rewrite the table? There also I think we can face a
similar problem if we directly send the statement, once the table will
be updated due to the DDL statement and then again due to table
rewrite as that will have a separate WAL.

Another somewhat unrelated problem I see with this work is how to save
recursion of the same command between nodes (when the involved nodes
replicate DDLs). For DMLs, we can avoid that via replication origins
as is being done in the patch proposed [1] but not sure how will we
deal with that here?

[1] - https://commitfest.postgresql.org/38/3610/

-- 
With Regards,
Amit Kapila.