I have a json array with a couple of records, all of which have 3 fields lat, lon, v.
I would like to create a select subquery from this array to join with another query. The problem is that I cannot make the example in the PostgreSQL documentation work.
select * from json_populate_recordset(null::x, '[{"a":1,"b":2},{"a":3,"b":4}]')
Should result in:
a | b
---+---
1 | 2
3 | 4
But I only get ERROR: type "x" does not exist Position: 45
It is necessary to pass a composite type to json_populate_recordset whereas a column list is passed to json_to_recordset:
select *
from json_to_recordset('[{"a":1,"b":2},{"a":3,"b":4}]') x (a int, b int)
;
a | b
---+---
1 | 2
3 | 4