Re: Materialized view rewrite is broken when there is an event trigger

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Michael Paquier <michael(at)paquier(dot)xyz>
Cc: Önder Kalacı <onderkalaci(at)gmail(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Re: Materialized view rewrite is broken when there is an event trigger
Date: 2022-08-09 14:35:01
Message-ID: 825329.1660055701@sss.pgh.pa.us
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Michael Paquier <michael(at)paquier(dot)xyz> writes:
> Please note that we should not add an event in create_am.sql even if
> it is empty, as it gets run in parallel of other tests so there could
> be interferences. I think that this had better live in
> sql/event_trigger.sql, even if it requires an extra table AM to check
> this specific case.

Agreed this is a bug, but I do not think we should add the proposed
regression test, regardless of where exactly. It looks like expending
a lot of cycles forevermore to watch for an extremely unlikely thing,
ie that we break this for ALTER MATERIALIZED VIEW and not anything
else.

I think the real problem here is that we don't have any mechanism
for verifying that table_rewrite_ok is correct. The "cross-check"
in EventTriggerCommonSetup is utterly worthless, as this failure
shows. Does it give any confidence at all that there are no other
mislabelings? I sure have none now. What can we do to verify that
more rigorously? Or maybe we should find a way to get rid of the
table_rewrite_ok flag altogether?

regards, tom lane

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