How to unnest and display elements of a JSON array?
According to the documentation, the #&gt; operator comes in useful:

-- name and genre of people (1 row per person)
select
    json_array_elements(
      t.test#&gt;'{clients, info}'
        )::json
    -&gt;&gt;'nom' as nom,
    json_array_elements(
      t.test#&gt;'{clients, info}'
        )::json
    -&gt;&gt;'genre' as genre
from my_table t


-- number of people, grouped by gender (1 row per gender)
select
      json_array_elements(
         t.test#&gt;'{clients, info}'
           )::json
           -&gt;&gt;'genre' as genre,
      count (t.*) as count
from my_table t
group by 1


SqlFiddle