Re: [PG19] Wrong results from NOT NULL-based expression simplification - Mailing list pgsql-hackers

On Sun, Oct 11, 2026 at 9:36 AM Richard Guo <guofenglinux@gmail.com> wrote:
> I plan to back-patch this to v19 only, after rc1.

Thanks for the patch!

Codex reported that the following INSERT, which previously succeeded, still
fails with this patch. I confirmed the issue. Should we fix this as well?

------------------------------------------
CREATE FUNCTION f(numeric) RETURNS numeric
LANGUAGE sql IMMUTABLE AS 'SELECT $1';

CREATE TABLE t (a numeric(10) NOT NULL);

CREATE UNIQUE INDEX ON t (
    NULLIF(f(a), CASE WHEN a IS NULL THEN a END)
);

INSERT INTO t VALUES (1)
ON CONFLICT (NULLIF(f(a), CASE WHEN a IS NULL THEN a END))
DO NOTHING;
------------------------------------------

Regards,

--
Fujii Masao