Date: Tue, 20 Oct 2020 16:04:20 -0300
From: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: Justin Pryzby <pryzby@telsasoft.com>
Cc: pgsql-hackers@postgresql.org, Amit Langote <amitlangote09@gmail.com>
Subject: Re: CREATE TABLE .. PARTITION OF fails to preserve tgenabled for
 inherited row triggers
Message-ID: <20201020190420.GA18579@alvherre.pgsql>
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On 2020-Sep-30, Justin Pryzby wrote:

> CREATE TABLE t(i int) PARTITION BY RANGE(i);
> CREATE TABLE t1 PARTITION OF t FOR VALUES FROM (1) TO (10);
> CREATE OR REPLACE FUNCTION tgf() RETURNS trigger LANGUAGE plpgsql AS $$ begin raise exception 'except'; end $$;
> CREATE TRIGGER tg AFTER INSERT ON t FOR EACH ROW EXECUTE FUNCTION tgf();
> ALTER TABLE t1 DISABLE TRIGGER tg;
> INSERT INTO t VALUES(1); -- inserts when trigger is disabled: good
> ALTER TABLE t DISABLE TRIGGER tg;
> CREATE TABLE t2 PARTITION OF t FOR VALUES FROM (10) TO (20);
> 
> postgres=# SELECT tgrelid::regclass, tgenabled FROM pg_trigger WHERE tgrelid::regclass::text IN ('t1','t2');
>  tgrelid | tgenabled 
> ---------+-----------
>  t1      | D
>  t2      | O
> (2 rows)
> 
> I consider this a bug,but CreateTrigStmt doesn't have any "enabled" member
> (since it's impossible to CREATE TRIGGER .. DISABLED), so I'm not sure where
> the fix should be.

Hmm, next question: should we backpatch a fix for this?  (This applies
all the way back to 11.)  If we do, then we would change behavior of
partition creation.  It's hard to see that the current behavior is
desirable ... and I think anybody who would have come across this, would
wish it behaved the other way.  But still -- it would definitely be a
behavior change.

This is a judgement call, and mine says to backpatch, but I've been
wrong on that.