missingIsNull;replacesAtt[Anum_pg_attribute_atthasmissing-1]=true;valuesAtt[Anum_pg_attribute_attmissingval-1]=missingval;replacesAtt[Anum_pg_attribute_attmissingval-1]=true;nullsAtt[Anum_pg_attribute_attmissingval-1]=missingIsNull;}atttup=heap_modify_tuple(atttup,RelationGetDescr(attrrel)...