gistfile1.txt

ecarroll=# explain SELECT j1.*, jsonb_typeof(j1.value) FROM jsonb_array_elements('[ 7,2, [6,7], 2,10 ]'::jsonb) AS j1 LEFT OUTER JOIN LATERAL jsonb_array_elements(j1."value") ON jsonb_typeof(j1.value) = 'array';
                                     QUERY PLAN                                      
-------------------------------------------------------------------------------------
 Nested Loop Left Join  (cost=0.01..251.25 rows=100 width=64)
   Join Filter: (jsonb_typeof(j1.value) = 'array'::text)
   ->  Function Scan on jsonb_array_elements j1  (cost=0.00..1.00 rows=100 width=32)
   ->  Function Scan on jsonb_array_elements  (cost=0.00..1.00 rows=100 width=0)
(4 rows)