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: Alexander Lakhin <exclusion@gmail.com>
Cc: Dean Rasheed <dean.a.rasheed@gmail.com>, Andrew Bille <andrewbille@gmail.com>, Peter Eisentraut <peter@eisentraut.org>, Robert Haas <robertmhaas@gmail.com>, pgsql-hackers@lists.postgresql.org
Date: 2024-04-24T17:36:17Z
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

On 2024-Apr-22, Alvaro Herrera wrote:

> > On d9f686a72~1 this script results in:
> > ERROR:  cannot change NO INHERIT status of inherited NOT NULL constraint "t_a_not_null" on relation "t"
> 
> Right.  Now I'm beginning to wonder if allowing ADD CONSTRAINT to mutate
> a pre-existing NO INHERIT constraint into a inheritable constraint
> (while accepting a constraint name in the command that we don't heed) is
> really what we want.  Maybe we should throw some error when the affected
> constraint is the topmost one, and only accept the inheritance status
> change when we're recursing.

So I added a restriction that we only accept such a change when
recursively adding a constraint, or during binary upgrade.  This should
limit the damage: you're no longer able to change an existing constraint
from NO INHERIT to YES INHERIT merely by doing another ALTER TABLE ADD
CONSTRAINT.

One thing that has me a little nervous about this whole business is
whether we're set up to error out where some child table down the
hierarchy has nulls, and we add a not-null constraint to it but fail to
do a verification scan.  I tried a couple of cases and AFAICS it works
correctly, but maybe there are other cases I haven't thought about where
it doesn't.

-- 
Álvaro Herrera               48°01'N 7°57'E  —  https://www.EnterpriseDB.com/
"You're _really_ hosed if the person doing the hiring doesn't understand
relational systems: you end up with a whole raft of programmers, none of
whom has had a Date with the clue stick."              (Andrew Sullivan)
https://postgr.es/m/20050809113420.GD2768@phlogiston.dyndns.org