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: Pg Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2023-02-28T19:15:37Z
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

Attachments

So I reworked this to use a new contype value for the NOT NULL
pg_constraint rows; I attach it here.  I think it's fairly clean.

0001 is just a trivial change that seemed obvious as soon as I ran into
the problem.

0002 is the most interesting part.

Things that are curious:

- Inheritance and primary keys.  If you have a table with a primary key,
and create a child of it, that child is going to have a NOT NULL in the
column that is the primary key.

- Inheritance and plain constraints.  It is not allowed to remove the
NOT NULL constraint from a child; currently, NO INHERIT constraints are
not supported.  I would say this is an useless feature, but perhaps not.

0003:
Since nobody liked the idea of listing the constraints in psql \d's
footer, I changed \d+ so that the "not null" column shows the name of
the constraint if there is one, or the string "(primary key)" if the
attnotnull marking for the column comes from the primary key.  The new
column is going to be quite wide in some cases; if we want to hide it
further, we could add the mythical \d++ and have *that* list the
constraint name, keeping \d+ as current.

-- 
Álvaro Herrera         PostgreSQL Developer  —  https://www.EnterpriseDB.com/
"Los trabajadores menos efectivos son sistematicamente llevados al lugar
donde pueden hacer el menor daño posible: gerencia."  (El principio Dilbert)