Create jsonb_unnest_recursive_distinct.sql

Author: rin-nas

functions/jsonb_unnest_recursive_distinct.sql

@@ -0,0 +1,65 @@
+create or replace function public.jsonb_unnest_recursive_distinct(data jsonb[])
+    returns table(
+        path  text[],
+        value jsonb,
+        member_of text
+    )
+    immutable
+    returns null on null input -- = strict
+    parallel safe -- Postgres 10 or later
+    security invoker
+    language sql
+    set search_path = ''
+as $func$
+    --explain (analyse)
+    with recursive r (path, value, member_of) as
+    (
+        select
+            distinct --!!! also fix performance problem
+            array[k.key],
+            v.value,
+            t.type
+        from unnest(jsonb_unnest_recursive_distinct.data) as u(data)
+        cross join jsonb_typeof(u.data) as t(type)
+        left join jsonb_each(case t.type when 'object' then u.data end) as o(obj_key, obj_value) on true
+        left join jsonb_array_elements(case t.type when 'array' then u.data end) with ordinality as a(arr_value, arr_key) on true
+        cross join coalesce(o.obj_key, (a.arr_key - 1)::text) as k(key)
+        cross join coalesce(o.obj_value, a.arr_value) as v(value)
+        where t.type in ('object', 'array')
+          and k.key is not null
+    union --all
+        select
+            array_append(r.path, k.key),
+            v.value,
+            t.type
+        from r
+        cross join jsonb_typeof(r.value) as t(type)
+        left join jsonb_each(case t.type when 'object' then r.value end) as o(obj_key, obj_value) on true
+        left join jsonb_array_elements(case t.type when 'array' then r.value end) with ordinality as a(arr_value, arr_key) on true
+        cross join coalesce(o.obj_key, (a.arr_key - 1)::text) as k(key)
+        cross join coalesce(o.obj_value, a.arr_value) as v(value)
+        where t.type in ('object', 'array')
+          and k.key is not null
+    )
+    select r.*
+    from r
+    where jsonb_typeof(r.value) not in ('object', 'array');
+$func$;
+
+comment on function public.jsonb_unnest_recursive_distinct(arr_data jsonb[])
+    is 'Recursive parse nested JSONs (arrays and objects), returns distinct keys and its values';
+
+------------------------------------------------------------------------------------------------------------------------
+--TEST
+
+do $$
+begin
+    assert (select count(*) = 9
+            from public.jsonb_unnest_recursive_distinct(array[
+                    '{"id":123,"g":null,"a":[9,8,4,5],"name":"unknown", "7": 3}'::jsonb,
+                    '{"id":123,"g":null,"a":[9,8,4,5],"name":"unknown", "7": 3}'::jsonb,
+                    '{"id":123,"g":null,"a":[9,8,4,5],"name":"unknown", "7": 2}'::jsonb
+                 ])
+           );
+end;
+$$;