Horton

Re: cataloguing NOT NULL constraints

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Alvaro Herrera <alvherre@alvh.no-ip.org>
Cc: Andres Freund <andres@anarazel.de>, Justin Pryzby <pryzby@telsasoft.com>, Peter Eisentraut <peter.eisentraut@enterprisedb.com>, pgsql-hackers@lists.postgresql.org
Date: 2023-04-09T20:11:42Z
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

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

Yeah, I've been thinking more about it, and this might also yield a
workable solution for the TestUpgrade breakage.  The idea would be,
roughly, for pg_dump to emit NOT NULL column decoration in all the
same places it does now, and then to drop it again immediately after
doing ADD PRIMARY KEY if it judges that there was no other reason
to have it.  This gets rid of the inconsistency for --binary-upgrade
which I think is what is causing the breakage.

I also ran into something else I didn't much care for:

regression=# create table foo(f1 int primary key, f2 int);
CREATE TABLE
regression=# create table foochild() inherits(foo);
CREATE TABLE
regression=# alter table only foo alter column f2 set not null;
ERROR:  cannot add constraint only to table with inheritance children
HINT:  Do not specify the ONLY keyword.

Previous versions accepted this case, and I don't really see why
we can't do so with this new implementation -- isn't this exactly
what pg_constraint.connoinherit was invented to represent?  Moreover,
existing pg_dump files can contain precisely this construct, so
blowing it off isn't going to be zero-cost.

			regards, tom lane