Re: cataloguing NOT NULL constraints

On Mon, Feb 5, 2024 at 5:51 PM Alvaro Herrera <alvherre@alvh.no-ip.org> wrote:
>
> On 2024-Feb-05, Alvaro Herrera wrote:
>
> > Hmm, let me have a look, I can probably get this one fixed today before
> > embarking on a larger fix elsewhere in the same feature.
>
> You know what -- this missing CCI has a much more visible impact, which
> is that the attnotnull marker that a primary key imposes on a partition
> is propagated early.  So this regression test no longer fails:
>
> create table cnn2_parted(a int primary key) partition by list (a);
> create table cnn2_part1(a int);
> alter table cnn2_parted attach partition cnn2_part1 for values in (1);
>
> Here, in the existing code the ALTER TABLE ATTACH fails with the error
> message that
>   ERROR:  primary key column "a" is not marked NOT NULL
> but with the patch, this no longer occurs.
>
> I'm not sure that this behavior change is desirable ... I have vague
> memories of people complaining that this sort of error was not very
> welcome ... but on the other hand it seems now pretty clear that if it
> *is* desirable, then its implementation is no good, because a single
> added CCI breaks it.
>
> I'm leaning towards accepting the behavior change, but I'd like to
> investigate a little bit more first, but what do others think?
>

if you place CommandCounterIncrement inside the `if (recurse)` branch,
then the regression test will be ok.

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 9f516967..25e225c2 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -7719,6 +7719,9 @@ set_attnotnull(List **wqueue, Relation rel,
AttrNumber attnum, bool recurse,

                         false));
                        retval |= set_attnotnull(wqueue, childrel, childattno,

  recurse, lockmode);
+
+                       CommandCounterIncrement();