The CData JDBC Driver for Elasticsearch supports standard SQL joins like the following examples.

Inner Join

An inner join selects only rows from both tables that match the join condition:

SELECT Customer.FirstName, Customer.LastName, Purchases.ItemName FROM Purchases INNER JOIN Customer ON Purchases.CustomerId = Customer.Id

Left Join

A left join selects all rows in the FROM table and only matching rows in the JOIN table:

 SELECT Customer.FirstName, Customer.LastName, Purchases.ItemName FROM Purchases LEFT JOIN Customer ON Purchases.CustomerId = Customer.Id