Horton

Re: cataloguing NOT NULL constraints

Peter Eisentraut <peter@eisentraut.org>

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From: Peter Eisentraut <peter@eisentraut.org>
To: Alvaro Herrera <alvherre@alvh.no-ip.org>, Dean Rasheed <dean.a.rasheed@gmail.com>
Cc: pgsql-hackers@lists.postgresql.org
Date: 2023-08-02T08:29:39Z
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 24.07.23 12:32, Alvaro Herrera wrote:
> However, 11.16 (<drop column not null clause> as part of 11.12 <alter
> column definition>), says that DROP NOT NULL causes the indication of
> the column as NOT NULL to be removed.  This, to me, says that if you do
> have multiple such constraints, you'd better remove them all with that
> command.  All in all, I lean towards allowing just one as best as we
> can.

Another clue is in 11.15 <set column not null clause>, which says

     1) Let C be the column identified by the <column name> CN in the
     containing <alter column definition>. If the column descriptor of C
     does not contain an indication that C is defined as NOT NULL, then:

     [do things]

Otherwise it does nothing.  So there can only be one such constraint per 
table.