From: Tom Lane <tgl@sss.pgh.pa.us>
To: Karsten Hilbert <Karsten.Hilbert@gmx.net>
cc: Alvaro Herrera <alvherre@2ndquadrant.com>,
        pgsql-general@lists.postgresql.org
Subject: Re: backend crash on DELETE, reproducible locally
In-reply-to: <20181101160007.GJ2954@hermes.hilbert.loc>
References: <20181101152723.zq2dtcgntmcmr4br@alvherre.pgsql>
 <18072.1541087036@sss.pgh.pa.us> <20181101160007.GJ2954@hermes.hilbert.loc>
Comments: In-reply-to Karsten Hilbert <Karsten.Hilbert@gmx.net>
	message dated "Thu, 01 Nov 2018 17:00:07 +0100"
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Date: Fri, 02 Nov 2018 23:56:58 -0400
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Karsten Hilbert <Karsten.Hilbert@gmx.net> writes:
> On Thu, Nov 01, 2018 at 11:43:56AM -0400, Tom Lane wrote:
>> Yeah, apparently we've passed a null OLD tuple to an RI_FKey_cascade_del
>> trigger, which surely shouldn't happen.  It'd be interesting to look at
>> the set of triggers on this table.  I don't entirely trust psql's \d
>> to show us reality if there's something screwed up about the triggers,
>> so in addition to \d output, could we see
>> select * from pg_trigger where tgrelid  = 'ref.auto_hint'::regclass;

> [ pretty normal-looking trigger entries ]

I was feeling baffled about this, but it suddenly occurs to me that maybe
the bug fixed in 040a1df61/372102b81 explains this.  If the particular
tuple you're trying to delete predates the last ALTER TABLE ADD COLUMN
operation on the table, then this bug would result in t_self getting
set to "invalid", which'd cause AfterTriggerSaveEvent to save "ate_ctid1"
as "invalid", which'd lead to a null tuple getting passed when the trigger
eventually gets invoked.

			regards, tom lane