select json_data.key , Sum(json_data.value::INTEGER) as value
from my_store, jsonb_each_text(my_jsonb_column) as json_data
group by json_data.key

from store in "my_store",
  inner_lateral_join: json_data in fragment("jsonb_each_text(?)", store.my_jsonb_column),
  group_by: json_data.key,
  select: %{
    key: json_data.key,
    value: sum(json_data.value)
  }