Implementing RavenDB aggregation queries using Java

RavenDB is an open source solution for document databases that can use Java to implement various aggregated queries. The following are the steps to implement various aggregation queries in RavenDB using Java: 1. Add Maven dependencies: First, add Maven dependencies for RavenDB in your Java project. You can add the following dependencies in the pom.xml file: <dependency> <groupId>net.ravendb.client</groupId> <artifactId>ravendb</artifactId> <version>5.1.3</version> </dependency> 2. Create RavenDB session: In Java code, you need to create a RavenDB session to interact with the database. try (IDocumentStore store = new DocumentStore("http://localhost:8080", "YourDatabaseName")) { store.initialize(); //Perform aggregation query operations here } 3. Execute aggregate query: Use RavenDB's Linq query syntax to execute aggregate queries. Here are some common examples of aggregation queries: -Total Statistics: long count = session.query(Order.class).count(); -Sum: double total = session.query(Order.class) .selectSumDouble(x -> x.getTotal()) .singleOrDefault(); -Average value: double average = session.query(Order.class) .selectAverageDouble(x -> x.getTotal()) .singleOrDefault(); -Maximum value: double max = session.query(Order.class) .selectMax(x -> x.getTotal()) .singleOrDefault(); -Minimum value: double min = session.query(Order.class) .selectMin(x -> x.getTotal()) .singleOrDefault(); 4. Filter criteria: Add filter criteria to the query. List<Order> orders = session.query(Order.class) .whereEquals("status", "InProgress") .toList(); 5. Grouping and Aggregation: Map<String, Double> averageByCategory = session.query(Order.class) .groupBy(x -> x.getCategory()) .selectKey(x -> x.getKey()) .selectSum(x -> x.getTotal()) .averageOn(x -> x.getTotal()) .toList(); This example will group orders by category and calculate the total and average amounts for each category. These are the basic steps for implementing various aggregated queries in RavenDB using Java. Please note that these are just some basic examples that you can adjust and expand according to your specific needs.