SELECT util.search_path_append('util');

SELECT mk_derived_col((:table_str, 'stemTag'),
$$concat_ws('.', "individual_tag", "stem_subtag")$$); -- runtime: 30 s ("Time: 29390.121 ms") @starscream
SELECT mk_derived_col((:table_str, 'tag'), $$"stemTag"$$); -- runtime: 25 s ("Time: 25010.752 ms") @starscream