curl -XPUT 'localhost:9200/_river/my_jdbc_river/_meta' -d '{
    "type" : "jdbc",
    "jdbc" : {
        "url" : "jdbc:mysql://localhost:3306/test",
        "user" : "",
        "password" : "",
        "sql" : "select products.name as "product.name", orders.customer as "product.customer.name", orders.quantity * products.price as "product.customer.bill" from products, orders where products.name = orders.product"
    }
}'

mysql> select products.name as "product.name", orders.customer as "product.customer", orders.quantity * products.price as "product.customer.bill" from products, orders where products.name = orders.product ;
+--------------+------------------+-----------------------+
| product.name | product.customer | product.customer.bill |
+--------------+------------------+-----------------------+
| Apples       | Big              |                     1 |
| Bananas      | Large            |                     2 |
| Oranges      | Huge             |                     6 |
| Apples       | Good             |                     2 |
| Oranges      | Bad              |                     9 |
+--------------+------------------+-----------------------+
5 rows in set, 5 warnings (0.00 sec)

id=0 {"product":{"name":"Apples","customer":{"bill":1.0,"name":"Big"}}}
id=1 {"product":{"name":"Bananas","customer":{"bill":2.0,"name":"Large"}}}
id=2 {"product":{"name":"Oranges","customer":{"bill":6.0,"name":"Huge"}}}
id=3 {"product":{"name":"Apples","customer":{"bill":2.0,"name":"Good"}}}
id=4 {"product":{"name":"Oranges","customer":{"bill":9.0,"name":"Bad"}}}