Re: Parameter NOT NULL to CREATE DOMAIN not the same as CHECK (VALUE IS NOT NULL)

From: Bruce Momjian <bruce(at)momjian(dot)us>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: jbe-mlist(at)magnetkern(dot)de, PostgreSQL-development <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Re: Parameter NOT NULL to CREATE DOMAIN not the same as CHECK (VALUE IS NOT NULL)
Date: 2025-01-30 13:26:54
Message-ID: Z5t-HtfrECeNegGZ@momjian.us
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On Wed, Jan 8, 2025 at 04:24:34PM -0500, Tom Lane wrote:
> Bruce Momjian <bruce(at)momjian(dot)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?

--
Bruce Momjian <bruce(at)momjian(dot)us> https://momjian.us
EDB https://enterprisedb.com

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

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