Re: BUG #15489: Segfault on DELETE

On Nov 7, 2018, at 8:33 PM, Amit Langote <Langote_Amit_f8@lab.ntt.co.jp> wrote:

Thanks Frederico for your reply.

On 2018/11/08 10:10, Frederico Costa Galvão wrote:

I stumbled upon this issue yesterday, and trying to reduce and pinpoint
it, I managed to get to this:

//start
CREATE TABLE a (
    id bigint
);

INSERT INTO a (id) VALUES (1); -- this id's value doesn't matter

ALTER TABLE ONLY a
    ADD CONSTRAINT a_pkey PRIMARY KEY (id);

CREATE TABLE b (
    a_id bigint
);

ALTER TABLE ONLY b
    ADD CONSTRAINT b_a_id_fkey FOREIGN KEY (a_id) REFERENCES a(id);

ALTER TABLE a ADD x BOOLEAN NOT NULL DEFAULT FALSE; -- or TRUE, doesn't
matter

There it is.  These are similar steps as I'd used to track down a bug
that's now fixed in 11.1.

https://www.postgresql.org/message-id/9cb4aa1c-12ba-59c3-fd75-545fa90fb92f%40lab.ntt.co.jp

The bug had to do with foreign key trigger not getting a proper
representation of the tuple being deleted, considering the newly added column.

-- VACUUM FULL ANALYZE a; -- uncomment this to fix the bug

Ah, VACUUM FULL will rewrite the tuples such that they're not hit by the
aforementioned bug.

So, if OP can tell that this is what happened in their case too, then 11.1
will have fixed the issue.

Thanks,
Amit