Horton

Re: cataloguing NOT NULL constraints

Alvaro Herrera <alvherre@alvh.no-ip.org>

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From: Alvaro Herrera <alvherre@alvh.no-ip.org>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Andres Freund <andres@anarazel.de>, Justin Pryzby <pryzby@telsasoft.com>, Peter Eisentraut <peter.eisentraut@enterprisedb.com>, pgsql-hackers@lists.postgresql.org
Date: 2023-04-09T19:11:01Z
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 2023-Apr-09, Tom Lane wrote:

> In the new dispensation, pg_dump omits the NOT NULL clauses.
> Great, you say, that makes the output more like what the user wrote.
> I'm not so sure.  This means that the ALTER TABLE will be compelled
> to perform a full-table scan to verify that there are no nulls in the
> already-loaded data before it can add the missing NOT NULL constraint.

Yeah, I agree that this unintended consequence isn't very palatable.  I
think the other pg_upgrade problem is easily fixed (haven't tried yet),
but having to rethink the pg_dump representation would likely take
longer than we'd like.

> I'm inclined to think that this idea of suppressing the implied
> NOT NULL from PRIMARY KEY is a nonstarter and we should just
> go ahead and make such a constraint.  Another idea could be for
> pg_dump to emit the NOT NULL, load data, do the ALTER ADD PRIMARY
> KEY, and then ALTER DROP NOT NULL.

I like that second idea, yeah.  It might be tough to make it work, but
I'll try.

> In any case, I wonder whether that's the sort of redesign we should
> be doing post-feature-freeze.  It might be best to revert and try
> again in v17.

Yeah, sounds like reverting for now and retrying in v17 with the
discussed changes might be better.

-- 
Álvaro Herrera         PostgreSQL Developer  —  https://www.EnterpriseDB.com/
"La espina, desde que nace, ya pincha" (Proverbio africano)