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Re: Support logical replication of DDLs

Jonathan S. Katz <jkatz@postgresql.org>

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From: "Jonathan S. Katz" <jkatz@postgresql.org>
To: Alvaro Herrera <alvherre@alvh.no-ip.org>
Cc: "houzj.fnst@fujitsu.com" <houzj.fnst@fujitsu.com>, Amit Kapila <amit.kapila16@gmail.com>, Ajin Cherian <itsajin@gmail.com>, Peter Smith <smithpb2250@gmail.com>, vignesh C <vignesh21@gmail.com>, Zheng Li <zhengli10@gmail.com>, li jie <ggysxcq@gmail.com>, Dilip Kumar <dilipbalaut@gmail.com>, Masahiko Sawada <sawada.mshk@gmail.com>, Japin Li <japinli@hotmail.com>, rajesh singarapu <rajesh.rs0541@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2023-02-16T19:43:16Z
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 2/16/23 2:38 PM, Alvaro Herrera wrote:
> On 2023-Feb-16, Jonathan S. Katz wrote:
> 
>> On 2/16/23 12:53 PM, Alvaro Herrera wrote:
> 
>>> I don't think this is the fault of logical replication.  Consider that
>>> for the backend server, the function source code is just an opaque
>>> string that is given to the plpgsql engine to interpret.  So there's no
>>> way for the logical DDL replication engine to turn this into runnable
>>> code if the table name is not qualified.
>>
>> Sure, that's fair. That said, the example above would fall under a "typical
>> use case", i.e. I'm replicating functions that call tables without schema
>> qualification. This is pretty common, and as logical replication becomes
>> used for more types of workloads (e.g. high availability), we'll definitely
>> see this.
> 
> Hmm, I think you're saying that replay should turn check_function_bodies
> off, and I think I agree with that.

Yes, exactly. +1

The docs seem to think that is the correct approach too:

"Set this parameter to off before loading functions on behalf of other 
users"[1].

[1] 
https://www.postgresql.org/docs/current/runtime-config-client.html#GUC-CHECK-FUNCTION-BODIES