PostgreSQL aggregate JSON recordset keys by row

  
postgresql_version

1
PostgreSQL 9.6.2, compiled by Visual C++ build 1800, 64-bit


  
id
data

1
1
[{"a": 1, "b": 2}, {"a": 3, "b":2}]

2
2
[{"a": 5, "b": 8}, {"a": 9, "b":0}]


  
id
sum
sum

1
1
4
4

2
2
14
8