Hazelcast IMDG is an open-source in-memory data grid that allows you to store and process large amounts of data in a distributed and highly scalable manner. One of the key features of Hazelcast IMDG is its ability to perform distributed queries, which allows you to query data across multiple nodes in the cluster.

In this blog post, we will explore how to work with Hazelcast IMDG distributed query in Java.

Setting Up Hazelcast IMDG Cluster

Before we dive into distributed queries, let’s set up a Hazelcast IMDG cluster. To do this, you need to add the Hazelcast IMDG dependency to your Maven or Gradle project:

<dependency>
    <groupId>com.hazelcast</groupId>
    <artifactId>hazelcast</artifactId>
    <version>4.2</version>
</dependency>

Next, you need to create a HazelcastInstance to connect to the Hazelcast IMDG cluster:

Config config = new Config();
HazelcastInstance hazelcastInstance = Hazelcast.newHazelcastInstance(config);

This will create a single Hazelcast IMDG node running on your local machine.

Performing Distributed Queries

Now that we have set up the Hazelcast IMDG cluster, let’s perform some distributed queries. Suppose we have a Map called employees where we store information about employees:

Map<Integer, Employee> employees = hazelcastInstance.getMap("employees");

To perform a distributed query, we can use the Predicate API provided by Hazelcast IMDG. For example, let’s find all employees with a salary greater than 5000:

Predicate predicate = Predicates.greaterThan("salary", 5000);
Collection<Employee> result = employees.values(predicate);

Here, we use the Predicates.greaterThan method to create a predicate that checks if the salary attribute is greater than 5000. We then pass this predicate to the values method to retrieve all the employees that satisfy the predicate.

Conclusion

In this blog post, we have explored how to work with Hazelcast IMDG distributed query in Java. We learned how to set up a Hazelcast IMDG cluster and perform distributed queries using the Predicate API. Distributed queries provide a powerful way to query data across multiple nodes in a distributed environment, enabling you to harness the true potential of Hazelcast IMDG.

#DistributedQuery #HazelcastIMDG