postgres
diff --git a/‎src/backend/catalog/information_schema.sql
+1-1 b/‎src/backend/catalog/information_schema.sql
+1-1
diff --git a/‎src/backend/catalog/pg_constraint.c
+44 b/‎src/backend/catalog/pg_constraint.c
+44
@@ -445,7 +445,7 @@ CREATE VIEW check_constraints AS
     SELECT current_database()::information_schema.sql_identifier AS constraint_catalog,
            rs.nspname::information_schema.sql_identifier AS constraint_schema,
            con.conname::information_schema.sql_identifier AS constraint_name,
-           pg_catalog.format('%s IS NOT NULL', at.attname)::information_schema.character_data AS check_clause
+           pg_catalog.format('%s IS NOT NULL', coalesce(at.attname, 'VALUE'))::information_schema.character_data AS check_clause
      FROM pg_constraint con
             LEFT JOIN pg_namespace rs ON rs.oid = con.connamespace
             LEFT JOIN pg_class c ON c.oid = con.conrelid
 
@@ -629,6 +629,50 @@ findNotNullConstraint(Oid relid, const char *colname)
 	return findNotNullConstraintAttnum(relid, attnum);
 }
 
+/*
+ * Find and return the pg_constraint tuple that implements a validated
+ * not-null constraint for the given domain.
+ */
+HeapTuple
+findDomainNotNullConstraint(Oid typid)
+{
+	Relation	pg_constraint;
+	HeapTuple	conTup,
+				retval = NULL;
+	SysScanDesc scan;
+	ScanKeyData key;
+
+	pg_constraint = table_open(ConstraintRelationId, AccessShareLock);
+	ScanKeyInit(&key,
+				Anum_pg_constraint_contypid,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(typid));
+	scan = systable_beginscan(pg_constraint, ConstraintRelidTypidNameIndexId,
+							  true, NULL, 1, &key);
+
+	while (HeapTupleIsValid(conTup = systable_getnext(scan)))
+	{
+		Form_pg_constraint con = (Form_pg_constraint) GETSTRUCT(conTup);
+
+		/*
+		 * We're looking for a NOTNULL constraint that's marked validated.
+		 */
+		if (con->contype != CONSTRAINT_NOTNULL)
+			continue;
+		if (!con->convalidated)
+			continue;
+
+		/* Found it */
+		retval = heap_copytuple(conTup);
+		break;
+	}
+
+	systable_endscan(scan);
+	table_close(pg_constraint, AccessShareLock);
+
+	return retval;
+}
+
 /*
  * Given a pg_constraint tuple for a not-null constraint, return the column
  * number it is for.