Horton

Re: BUG #18500: Detaching a partition with an index manually attached to the parent's index triggers Assert

Michael Paquier <michael@paquier.xyz>

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From: Michael Paquier <michael@paquier.xyz>
To: Alvaro Herrera <alvherre@alvh.no-ip.org>
Cc: Tender Wang <tndrwang@gmail.com>, exclusion@gmail.com, pgsql-bugs@lists.postgresql.org
Date: 2024-06-29T00:15:09Z
Lists: pgsql-bugs

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  1. Fix ALTER TABLE DETACH for inconsistent indexes

On Fri, Jun 28, 2024 at 01:27:17PM +0200, Alvaro Herrera wrote:
> I guess you could also fix this by adding a PK constraint to the parent
> table, so that the situation is consistent in the other direction.

Yes, I've also considered this option when thinking about this thread,
but forcing a constraint creation up to the parent felt non-intuitive
to me as we force creation of catalog entries on the children based on
the state of the parent for basically everything else.  So introducing
a new path where we would do the reverse is a recipe for more complex
code in tablecmds.c, which I'd rather avoid.

> Here's a proposed patch for master only.  It turns all three situations
> being reported into ereport(ERROR); in one case I have an XXX comment,
> because we have an alternative when attaching a partition that already
> has a PK to a partitioned table that has a non-PK index: just create a
> separate index in the partition.  But that would cause slowness, which
> is probably undesirable.  I'm inclined to just remove the XXX comment,
> but if anyone has other thoughts, they are welcome.

An error sounds saner here in the long term.

Tests for all of the code paths involved, perhaps?  ;)
--
Michael