Use system built-in function in Flink Table api

Question

I'm struggling to use the system built-in functions in flink table api. In particular the ROW_NUMBER() function. I saw some examples but all of them were in Flink SQL and I'm looking for table api syntax. I read that there is no any table api function for ROW_NUMBER so I tried to use Expression.callSql(..) with no success. Thanks for any help!

Answer 1

Like you've already mentioned, there's no Table API function for ROW_NUMBER so the only way you can use them, is by executing SQL directly in your Table API application via something like:

tableEnv.sqlQuery(
        String.join(
                "\n",
                "SELECT id AS order_id",
                "order_time",
                "ROW_NUMBER() OVER (PARTITION BY id ORDER BY order_time) AS rownum",
                "FROM Customers");