Re: not null constraints, again

hi.

heap_create_with_catalog argument (cooked_constraints):
passed as NIL in function {create_toast_table, make_new_heap}
passed as list_concat(cookedDefaults,old_constraints) in DefineRelation

in DefineRelation we have function call:
MergeAttributes
heap_create_with_catalog
StoreConstraints

StoreConstraints second argument: cooked_constraints, some is comes from
DefineRelation->MergeAttributes old_constraints:
{
stmt->tableElts = MergeAttributes(stmt->tableElts, inheritOids,
stmt->relation->relpersistence, stmt->partbound != NULL, &old_constraints,
&old_notnulls);
}

My understanding from DefineRelation->MergeAttributes is that old_constraints
will only have CHECK constraints.
that means heap_create_with_catalog->StoreConstraints
StoreConstraints didn't actually handle CONSTR_NOTNULL.

heap_create_with_catalog comments also says:
* cooked_constraints: list of precooked check constraints and defaults

coverage https://coverage.postgresql.org/src/backend/catalog/heap.c.gcov.html
also shows StoreConstraints, CONSTR_NOTNULL never being called,
which is added by this thread.

my question is can we remove StoreConstraints, CONSTR_NOTNULL handling.
we have 3 functions {StoreConstraints, AddRelationNotNullConstraints,
AddRelationNewConstraints} that will call StoreRelNotNull to store the not-null
constraint. That means if we want to bullet proof that something is conflicting
with not-null, we need to add code to check all these 3 places.
removing StoreConstraints handling not-null seems helpful.

also comments in MergeAttributes:
* Output arguments:
* 'supconstr' receives a list of constraints belonging to the parents,
* updated as necessary to be valid for the child.
* 'supnotnulls' receives a list of CookedConstraints that corresponds to
* constraints coming from inheritance parents.

can we be explicit that "supconstr" is only about CHECK constraint,
"supnotnulls" is
only about NOT-NULL constraint.