Horton

Re: cataloguing NOT NULL constraints

Dean Rasheed <dean.a.rasheed@gmail.com>

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From: Dean Rasheed <dean.a.rasheed@gmail.com>
To: Alvaro Herrera <alvherre@alvh.no-ip.org>
Cc: Robert Haas <robertmhaas@gmail.com>, Peter Eisentraut <peter@eisentraut.org>, pgsql-hackers@lists.postgresql.org
Date: 2023-08-05T11:35:02Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Revert structural changes to not-null constraints

  2. Fix inconsistencies in error messages

  3. Disallow direct change of NO INHERIT of not-null constraints

  4. Disallow NO INHERIT not-null constraints on partitioned tables

  5. Better handle indirect constraint drops

  6. Don't try to assign smart names to constraints

  7. Fix restore of not-null constraints with inheritance

  8. ATTACH PARTITION: Don't match a PK with a UNIQUE constraint

  9. Fix propagating attnotnull in multiple inheritance

  10. Check stack depth in new recursive functions

  11. Move privilege check to the right place

  12. Update information_schema definition for not-null constraints

  13. Fix not-null constraint test

  14. Disallow changing NO INHERIT status of a not-null constraint

  15. Catalog not-null constraints

  16. parallel_schedule: add comment on event_trigger test dependency

  17. Revert "Catalog NOT NULL constraints" and fallout

  18. Adjust contrib/sepgsql regression test expected outputs.

  19. Fix table name clash in recently introduced test

  20. Catalog NOT NULL constraints

  21. Change the rules for inherited CHECK constraints to be essentially the same

On Fri, 4 Aug 2023 at 19:10, Alvaro Herrera <alvherre@alvh.no-ip.org> wrote:
>
> On 2023-Jul-28, Alvaro Herrera wrote:
>
> > To avoid that, one option would be to make this NN constraint
> > undroppable ...  but I don't see how.  One option might be to add a
> > pg_depend row that links the NOT NULL constraint to its PK constraint.
> > But this will be a strange case that occurs nowhere else, since other
> > NOT NULL constraint don't have such pg_depend rows.  Also, I won't know
> > how pg_dump likes this until I implement it.
>
> I've been completing the implementation for this.  It seems to work
> reasonably okay; pg_dump requires somewhat strange contortions, but they
> are similar to what we do in flagInhTables already, so I don't feel too
> bad about that.
>
> What *is* odd and bothersome is that it also causes a problem dropping
> the child table.
>

Hmm, thinking about this some more, I think this might be the wrong
approach to fixing the original problem. I think it was probably OK
that the NOT NULL constraint on the child was marked as inherited, but
I think what should have happened is that dropping the PRIMARY KEY
constraint on the parent should have caused the NOT NULL constraint on
the child to have been deleted (in the same way as it would have been,
if it had been a NOT NULL constraint on the parent).

Regards,
Dean