SELECT DISTINCT in JSON column in postgresql

Question

I have a table that has 2 columns, id (int auto_increment) and Resp (json).

In this table I have duplicate values in the column Resp, something like that:

id | resp
--------------------------------------------
1  | {"nome": "Jonh Doe", "idade": 20} 
2  | {"nome": "Jonh Doe", "idade": 20}
3  | {"nome": "Maria Claire", "idade": 38} 
4  | {"nome": "James Connor", "idade": 50} 

I’d just need to make a famous and traditional SELECT DISTINCT resp FROM tabela, however on account of the column resp be the type JSON, I cannot do DISTINCT, Postgresql returns the following message:

ERROR:  could not identify an equality operator for type json

I have already researched some solutions and tried the following ones, but they did not work:

Attempt 1:

SELECT
  DISTINCT field
FROM (
  SELECT jsonb_object_keys(resp) AS field
  FROM public.tabela
    ) AS subquery
--------------
ERROR: function jsonb_object_keys(json) does not exist

Attempt 2:

SELECT
  DISTINCT field
FROM (
  SELECT jsonb_array_elements(resp) AS field
  FROM public.tabela
    ) AS subquery
--------------
ERROR: function jsonb_array_elements(json) does not exist

Attempt 3:

SELECT
  DISTINCT field
FROM (
  SELECT json_array_elements(resp) AS field
  FROM public.tabela
    ) AS subquery
--------------
ERROR: could not identify an equality operator for type json

Answer 1

In the postgresql you can YES group by columns of the json, you only need to specify the columns that should serve for grouping. In this post (en) you can see how; your consultation would look like this:

select val->>'nome' as field, val->>'idade' as age, count(*) as total 
from tabelateste 
group by val->>'nome', val->>'idade'

Look here one fiddle working.