Apache Cassandra Aggregation Query

Apache Cassandra supports multiple aggregation queries, including count, sum, average, minimum, maximum, and more. These aggregate queries are implemented by using Cassandra's aggregate functions and other Intrinsic function. Before introducing various aggregation queries, let's assume a simple example table structure to store user order information: sql CREATE TABLE orders ( user_id UUID, order_id UUID, product_name TEXT, quantity INT, total_price DECIMAL, PRIMARY KEY (user_id, order_id) ); Now we will use this table structure to demonstrate examples of various aggregated queries: 1. Count query: Calculate the total number of a certain field. sql SELECT COUNT(*) FROM orders; This will return the total number of rows in the order table. 2. Sum query: Calculate the sum of a certain field. sql SELECT SUM(quantity) FROM orders; This will return the sum of the product quantities for all orders in the order table. 3. Average value query: Calculate the average value of a certain field. sql SELECT AVG(total_price) FROM orders; This will return the average total price of all orders. 4. Minimum value query: Find the minimum value of a certain field. sql SELECT MIN(quantity) FROM orders; This will return the minimum product quantity in the order table. 5. Maximum value query: Find the maximum value of a certain field. sql SELECT MAX(total_price) FROM orders; This will return the maximum total price in the order table. It should be noted that in order to obtain accurate results, aggregation queries should be executed on appropriate partitioning keys, so that data can be evenly distributed between nodes. It should be noted that Cassandra does not support complex aggregate queries such as JOIN and GROUP BY. If you need these features, you can consider using other databases, such as Apache Spark or Elasticsearch.