Subject: Re: MERGE lacks ruleutils.c decompiling support!?

From: Alvaro Herrera <[email-masked]>
Date: Fri, 5 May 2023 18:21:30 +0200

On 2023-May-05, Tom Lane wrote:

> I made this function:
> 
> CREATE OR REPLACE FUNCTION test_fun()
> RETURNS void
> LANGUAGE SQL
> BEGIN ATOMIC
> MERGE INTO target
> USING source s on s.id = target.id
> WHEN MATCHED THEN
>   UPDATE SET data = s.data
> WHEN NOT MATCHED THEN
>   INSERT VALUES (s.id, s.data);
> end;
> 
> It appears to work fine, but:
> 
> regression=# \sf+ test_fun()
> ERROR:  unrecognized query command type: 5
> 
> and it also breaks pg_dump.  Somebody screwed up pretty badly
> here.  Is there any hope of fixing it for Monday's releases?
> 
> (I'd guess that decompiling the WHEN clause would take a nontrivial
> amount of new code, so maybe fixing it on such short notice is
> impractical.  But ugh.)

Hmm, there is *some* code in ruleutils for MERGE, but clearly something
is missing.  Let me have a look ...

-- 
Álvaro Herrera         PostgreSQL Developer  —  https://www.EnterpriseDB.com/