Horton

Re: information_schema and not-null constraints

David G. Johnston <david.g.johnston@gmail.com>

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From: "David G. Johnston" <david.g.johnston@gmail.com>
To: Vik Fearing <vik@postgresfriends.org>
Cc: Alvaro Herrera <alvherre@alvh.no-ip.org>, Pg Hackers <pgsql-hackers@lists.postgresql.org>, Tom Lane <tgl@sss.pgh.pa.us>, Peter Eisentraut <peter@eisentraut.org>, Peter Eisentraut <peter.eisentraut@enterprisedb.com>
Date: 2023-09-05T22:14:15Z
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 Tue, Sep 5, 2023 at 2:50 PM Vik Fearing <vik@postgresfriends.org> wrote:

> On 9/5/23 19:15, Alvaro Herrera wrote:
> > On 2023-Sep-05, Alvaro Herrera wrote:
> >
> > Looking now at what to do for CHECK_CONSTRAINTS with domain constraints,
> > I admit I'm completely confused about what this view is supposed to
> > show.  Currently, we show the constraint name and a definition like
> > "CHECK (column IS NOT NULL)".  But since the table name is not given, it
> > is not possible to know to what table the column name refers to.  For
> > domains, we could show "CHECK (VALUE IS NOT NULL)" but again with no
> > indication of what domain it applies to, or anything at all that would
> > make this useful in any way whatsoever.
>
> Constraint names are supposed to be unique per schema[1] so the view
> contains the minimum required information to identify the constraint.
>

I'm presuming that the view constraint_column_usage [1] is an integral part
of all this though I haven't taken the time to figure out exactly how we
are implementing it today.

I'm not all that for either A or B since the status quo seems workable.
Though ideally if the system has unique names per schema then everything
should just work - having the views produce duplicated information (as
opposed to nothing) if they are used when the DBA doesn't enforce the
standard's requirements seems plausible.

David J.

[1]
https://www.postgresql.org/docs/current/infoschema-constraint-column-usage.html