Date: Mon, 7 Apr 2025 21:34:06 -0400
From: Bruce Momjian <bruce@momjian.us>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: jbe-mlist@magnetkern.de,
	PostgreSQL-development <pgsql-hackers@lists.postgresql.org>
Subject: Re: Parameter NOT NULL to CREATE DOMAIN not the same as CHECK (VALUE
 IS NOT NULL)
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On Thu, Jan 30, 2025 at 08:26:54AM -0500, Bruce Momjian wrote:
> On Wed, Jan  8, 2025 at 04:24:34PM -0500, Tom Lane wrote:
> > Bruce Momjian <bruce@momjian.us> writes:
> > > I think this needs some serious research.
> > 
> > We've discussed this topic before.  The spec's definition of IS [NOT]
> > NULL for composite values is bizarre to say the least.  I think
> > there's been an intentional choice to keep most NOT NULL checks
> > "simple", that is we look at the overall value's isnull bit and
> > don't probe any deeper than that.
> > 
> > If the optimizations added in v17 changed existing behavior,
> > I agree that's bad.  We should probably fix it so that those
> > are only applied when argisrow is false.
> 
> I have developed the attached patch using your argisrow suggestion which
> fixes the test I posted.  Is this something we should backpatch?

Patch applied.  This fix will appear in the next minor PG 17 release.

-- 
  Bruce Momjian  <bruce@momjian.us>        https://momjian.us
  EDB                                      https://enterprisedb.com

  Do not let urgent matters crowd out time for investment in the future.