Unindex Postgresql

The issue of foreign keys without indexing was the starting point of my blog. Just browsing and I found a postgresql version of unindex query. Copied the query here. Visit the original authors page for more explanation and an example. Expecially liked the commented code /*the first index columns must be the same as the key columns, but order doesn't matter*/.

SELECT c.conrelid::regclass AS "table",
       /* list of key column names in order */
       string_agg(a.attname, ',' ORDER BY x.n) AS columns,
       pg_catalog.pg_size_pretty(
          pg_catalog.pg_relation_size(c.conrelid)
       ) AS size,
       c.conname AS constraint,
       c.confrelid::regclass AS referenced_table,
       'create index '||c.conname||'_idx on '||c.conrelid::regclass||'('||string_agg(a.attname, ',' ORDER BY x.n)||');' idx
FROM pg_catalog.pg_constraint c
   /* enumerated key column numbers per foreign key */
   CROSS JOIN LATERAL
      unnest(c.conkey) WITH ORDINALITY AS x(attnum, n)
   /* name for each key column */
   JOIN pg_catalog.pg_attribute a
      ON a.attnum = x.attnum
         AND a.attrelid = c.conrelid
WHERE NOT EXISTS
        /* is there a matching index for the constraint? */
        (SELECT 1 FROM pg_catalog.pg_index i
         WHERE i.indrelid = c.conrelid
           /* the first index columns must be the same as the
              key columns, but order doesn't matter */
           AND (i.indkey::smallint[])[0:cardinality(c.conkey)-1]
               @> c.conkey)
  AND c.contype = 'f'
GROUP BY c.conrelid, c.conname, c.confrelid
ORDER BY pg_catalog.pg_relation_size(c.conrelid) DESC;