From: Tom Lane <tgl@sss.pgh.pa.us>
To: Mark Dilger <mark.dilger@enterprisedb.com>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Subject: Re: logical replication of truncate command with trigger causes Assert
Date: Tue, 08 Jun 2021 18:55:46 -0400
Message-ID: <1250962.1623192946@sss.pgh.pa.us> (raw)
In-Reply-To: <B4A3AF82-79ED-4F4C-A4E5-CD2622098972@enterprisedb.com>
References: <B4A3AF82-79ED-4F4C-A4E5-CD2622098972@enterprisedb.com>
Mark Dilger <mark.dilger@enterprisedb.com> writes:
> On master, when a statement level trigger is fired for a replicated truncate command, the following stack trace is generated:
Hmm.
> I believe the issue was introduced in commit 84f5c2908da which added EnsurePortalSnapshotExists. That's not going to work in the case of logical replication, because there isn't an ActivePortal nor a snapshot.
The right way to say that is "commit 84f5c2908da exposed the pre-existing
unsafe behavior of this code". It's not okay to run arbitrary user code
without holding a snapshot to protect TOAST dereference operations.
I suppose that either apply_dispatch or LogicalRepApplyLoop needs to
grow some more snapshot management logic, but I've not looked at that
code much, so I don't have an opinion on just where to add it.
There's a reasonable case to be made that running user code outside
a Portal is a just-plain-bad idea, so we should fix the logical
apply worker to make it create a suitable Portal. I speculated about
that in the commit message for 84f5c2908da, but I don't feel like
taking point on such work.
regards, tom lane
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To: pgsql-hackers@postgresql.org
Cc: tgl@sss.pgh.pa.us, mark.dilger@enterprisedb.com, pgsql-hackers@lists.postgresql.org
Subject: Re: logical replication of truncate command with trigger causes Assert
In-Reply-To: <1250962.1623192946@sss.pgh.pa.us>
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