Implementing GridGain aggregation queries using Java
GridGain is an open source in memory computing platform that provides rich aggregation query capabilities. The following are the steps to implement various data aggregation queries in GridGain using Java:
1. Add the Maven dependency coordinates of GridGain to the pom.xml file of the project:
<dependency>
<groupId>org.apache.ignite</groupId>
<artifactId>ignite-core</artifactId>
<version>2.9.1</version>
</dependency>
2. Create a GridGain configuration file ignite config.xml and add relevant configuration items, such as cluster node configuration, cache configuration, etc. Taking the implementation of aggregation queries on a simple Person object as an example, the configuration file can be as follows:
<beans xmlns="http://www.springframework.org/schema/beans"
...
xsi:schemaLocation="...">
<!-- Grid configuration -->
<bean id="ignite.cfg" class="org.apache.ignite.configuration.IgniteConfiguration">
...
<!-- Cache configuration -->
<property name="cacheConfiguration">
<list>
<bean class="org.apache.ignite.configuration.CacheConfiguration">
<property name="name" value="personCache"/>
<property name="indexedTypes">
<list>
<value>com.example.Person</value>
</list>
</property>
</bean>
</list>
</property>
</bean>
</beans>
3. Write a Person class that should have the type specified by 'indexedTypes' in the GridGain cache configuration:
import org.apache.ignite.cache.query.annotations.QuerySqlField;
public class Person {
@QuerySqlField(index = true)
private String name;
@QuerySqlField
private int age;
// Getters and Setters
}
4. Create a GridGain node and start:
import org.apache.ignite.Ignite;
import org.apache.ignite.Ignition;
import org.apache.ignite.configuration.IgniteConfiguration;
public class GridGainExample {
public static void main(String[] args) {
IgniteConfiguration cfg = new IgniteConfiguration();
cfg.setIgniteInstanceName("gridNode");
cfg.setPeerClassLoadingEnabled(true);
Cfg. setConfigurationFilePath ("path/to/ignite config. xml")// Set GridGain configuration file path
Ignite ignite = Ignition.start(cfg);
//Perform aggregation query operations here
}
}
5. Perform aggregation query operations. Here are some example codes for common aggregation query operations:
import org.apache.ignite.Ignite;
import org.apache.ignite.IgniteCache;
import org.apache.ignite.Ignition;
import org.apache.ignite.configuration.IgniteConfiguration;
import org.apache.ignite.lang.IgniteBiPredicate;
import org.apache.ignite.stream.StreamTransformer;
import javax.cache.Cache;
import java.util.Collection;
import java.util.Map;
public class GridGainExample {
public static void main(String[] args) {
IgniteConfiguration cfg = new IgniteConfiguration();
cfg.setIgniteInstanceName("gridNode");
cfg.setPeerClassLoadingEnabled(true);
Cfg. setConfigurationFilePath ("path/to/ignite config. xml")// Set GridGain configuration file path
Ignite ignite = Ignition.start(cfg);
IgniteCache<Long, Person> cache = ignite.getOrCreateCache("personCache");
//Statistical age sum
double sum = cache.query()
.aggregate(GridSumFunction.class)
.execute();
System.out.println("Sum: " + sum);
//Calculate maximum age
int maxAge = cache.query()
.aggregate(GridMaxFunction.class)
.execute();
System.out.println("Max Age: " + maxAge);
//Counting the number of people of different ages
Map<Integer, Long> countByAge = cache.query()
.aggregate(GridCountByAgeFunction.class)
.execute();
System.out.println("Count by Age: " + countByAge);
//Query information of individuals aged over 30
Collection<Cache.Entry<Long, Person>> personsOver30 = cache.query()
.filter(new IgniteBiPredicate<Long, Person>() {
@Override
public boolean apply(Long key, Person person) {
return person.getAge() > 30;
}
})
.getAll();
System.out.println("Persons over 30: " + personsOver30);
//Other aggregation query operations can refer to the official documentation of GridGain
}
}
Note: In the above code, 'GridSumFunction', 'GridMaxFunction', and 'GridCountByAgeFunction' are custom GridGain aggregation functions that you need to implement according to your actual needs. These functions need to implement the 'org. apache. ignite. cache. affinity. AffinityKeyMapped' interface for partitioning cached data.
This is the process of using Java to implement various data aggregation queries for GridGain. You can implement more complex aggregation query operations based on specific requirements and the official GridGain documentation.
