-- if the output of following query changes, we might need to change
-- some heap_getattr() calls to heap_deform_tuple(). This errors out in
-- postgres versions before 11.
SELECT attrelid::regclass, attname, atthasmissing, attmissingval
FROM pg_attribute
WHERE atthasmissing
ORDER BY attrelid, attname;
   attrelid   |    attname     | atthasmissing | attmissingval 
--------------+----------------+---------------+---------------
 pg_dist_node | hasmetadata    | t             | {f}
 pg_dist_node | isactive       | t             | {t}
 pg_dist_node | metadatasynced | t             | {f}
 pg_dist_node | nodecluster    | t             | {default}
 pg_dist_node | noderole       | t             | {primary}
(5 rows)