Let us understand the execution life cycle of a query.
- Here is the query
SELECT order_item_order_id, sum(order_item_subtotal) AS order_revenue FROM order_items GROUP BY order_item_subtotal LIMIT 10;
Once the query is submitted, this is what happens.
- Syntax and Semantecs Check
- Compile Hive query into Map Reduce application
- Submit Map Reduce Application as one or more Job
- Execute all the associated Map Reduce Jobs