Re: not null constraints, again

static Oid
StoreRelNotNull(Relation rel, const char *nnname, AttrNumber attnum,
bool is_validated, bool is_local, int inhcount,
bool is_no_inherit)
{
Oid constrOid;
Assert(attnum > InvalidAttrNumber);
constrOid =
CreateConstraintEntry(nnname,
RelationGetNamespace(rel),
CONSTRAINT_NOTNULL,
false,
false,
is_validated
....
}
is is_validated always true, can we add an Assert on it?

in AddRelationNotNullConstraints
for (int outerpos = 0; outerpos < list_length(old_notnulls); outerpos++)
{
}
CookedConstraint struct already has "int inhcount;"
can we rely on that, rather than using add_inhcount?
we can also add an Assert: "Assert(!cooked->is_no_inherit);"

I've put these points into a patch,
please check the attached.

/*
* Remember primary key index, if any. We do this only if the index
* is valid; but if the table is partitioned, then we do it even if
* it's invalid.
*
* The reason for returning invalid primary keys for foreign tables is
* because of pg_dump of NOT NULL constraints, and the fact that PKs
* remain marked invalid until the partitions' PKs are attached to it.
* If we make rd_pkindex invalid, then the attnotnull flag is reset
* after the PK is created, which causes the ALTER INDEX ATTACH
* PARTITION to fail with 'column ... is not marked NOT NULL'. With
* this, dropconstraint_internal() will believe that the columns must
* not have attnotnull reset, so the PKs-on-partitions can be attached
* correctly, until finally the PK-on-parent is marked valid.
*
* Also, this doesn't harm anything, because rd_pkindex is not a
* "real" index anyway, but a RELKIND_PARTITIONED_INDEX.
*/
if (index->indisprimary &&
(index->indisvalid ||
relation->rd_rel->relkind == RELKIND_PARTITIONED_TABLE))
{
pkeyIndex = index->indexrelid;
pkdeferrable = !index->indimmediate;
}
The comment (especially paragraph "The reason for returning invalid
primary keys") is overwhelming.
Can you also add some sql examples into the comments.
I guess some sql examples, people can understand it more easily?