Обсуждение: JSON path query returns duplicate values

Hello,

I wonder why this query

   select jsonb_path_query_array(col, '$.**.itemName')
   from (
     values ('{"items": [{"itemName": "a", "items": [{"itemName": "b"}]}]}'::jsonb)
   ) as t(col)

returns each itemName twice: ["a", "a", "b", "b"]

I would have expected: ["a", "b"]

Thomas

Thomas Kellerer schrieb am 21.12.2020 um 10:43:
> I wonder why this query
>
>    select jsonb_path_query_array(col, '$.**.itemName')
>    from (
>      values ('{"items": [{"itemName": "a", "items": [{"itemName": "b"}]}]}'::jsonb)
>    ) as t(col)
>
> returns each itemName twice: ["a", "a", "b", "b"]
>
> I would have expected: ["a", "b"]

Is this a bug or intended?

If it's intended, I would really like to know the reason.
At least to me the result is quite surprsing.