Using Java to Implement Aerospike Aggregation Queries
Using Java to implement various aggregation queries for Aerospike can be achieved through Aerospike's Java client library. Here are some common examples of aggregation queries and corresponding Java code examples:
1. Count aggregation query
Use the 'COUNT' aggregate function to count the records in the specified set.
import com.aerospike.client.*;
import com.aerospike.client.query.*;
import com.aerospike.client.task.*;
public class AerospikeCountAggregation {
public static void main(String[] args) {
AerospikeClient client = new AerospikeClient("localhost", 3000);
Statement stmt = new Statement();
stmt.setNs("test");
stmt.setSetName("demo");
ResultSet resultSet = client.queryAggregate(null, stmt, "demo", "countUDF", "count");
try {
while (resultSet.next()) {
Object result = resultSet.getObject();
System.out.println("Record count: " + result);
}
} finally {
resultSet.close();
client.close();
}
}
}
Note: 'countUDF' is a Lua function registered using Aerospike to calculate the number of records.
2. Sum aggregation query
Use the 'SUM' aggregation function to calculate the sum of records in a specified set.
import com.aerospike.client.*;
import com.aerospike.client.query.*;
import com.aerospike.client.task.*;
public class AerospikeSumAggregation {
public static void main(String[] args) {
AerospikeClient client = new AerospikeClient("localhost", 3000);
Statement stmt = new Statement();
stmt.setNs("test");
stmt.setSetName("demo");
ResultSet resultSet = client.queryAggregate(null, stmt, "demo", "sumUDF", "sum");
try {
while (resultSet.next()) {
Object result = resultSet.getObject();
System.out.println("Sum of values: " + result);
}
} finally {
resultSet.close();
client.close();
}
}
}
Similar to count aggregation queries, 'sumUDF' is a Lua function registered using Aerospike to calculate the sum of records.
3. Average Aggregation Query
Use the 'AVG' aggregation function to calculate the average value of records in a specified set.
import com.aerospike.client.*;
import com.aerospike.client.query.*;
import com.aerospike.client.task.*;
public class AerospikeAverageAggregation {
public static void main(String[] args) {
AerospikeClient client = new AerospikeClient("localhost", 3000);
Statement stmt = new Statement();
stmt.setNs("test");
stmt.setSetName("demo");
ResultSet resultSet = client.queryAggregate(null, stmt, "demo", "avgUDF", "avg");
try {
while (resultSet.next()) {
Object result = resultSet.getObject();
System.out.println("Average value: " + result);
}
} finally {
resultSet.close();
client.close();
}
}
}
Similar to count aggregation queries, 'avgUDF' is a Lua function registered using Aerospike to calculate the average value of records.
4. Find the maximum aggregation query
Use the 'MAX' aggregation function to calculate the maximum value of records in a specified set.
import com.aerospike.client.*;
import com.aerospike.client.query.*;
import com.aerospike.client.task.*;
public class AerospikeMaxAggregation {
public static void main(String[] args) {
AerospikeClient client = new AerospikeClient("localhost", 3000);
Statement stmt = new Statement();
stmt.setNs("test");
stmt.setSetName("demo");
ResultSet resultSet = client.queryAggregate(null, stmt, "demo", "maxUDF", "max");
try {
while (resultSet.next()) {
Object result = resultSet.getObject();
System.out.println("Maximum value: " + result);
}
} finally {
resultSet.close();
client.close();
}
}
}
Similar to counting aggregation queries, 'maxUDF' is a Lua function registered using Aerospike to calculate the maximum value of records.
5. Finding the Minimum Aggregate Query
Use the 'MIN' aggregation function to calculate the minimum value of records in a specified set.
import com.aerospike.client.*;
import com.aerospike.client.query.*;
import com.aerospike.client.task.*;
public class AerospikeMinAggregation {
public static void main(String[] args) {
AerospikeClient client = new AerospikeClient("localhost", 3000);
Statement stmt = new Statement();
stmt.setNs("test");
stmt.setSetName("demo");
ResultSet resultSet = client.queryAggregate(null, stmt, "demo", "minUDF", "min");
try {
while (resultSet.next()) {
Object result = resultSet.getObject();
System.out.println("Minimum value: " + result);
}
} finally {
resultSet.close();
client.close();
}
}
}
Similar to counting aggregation queries, 'minUDF' is a Lua function registered using Aerospike to calculate the minimum value of records.
The 'client' object in the above example code is the main object in Aerospike's Java client library, which is used to interact with the Aerospike database. The statement object in the sample code is used to set the namespace and collection name of the query, as well as other query conditions.
You need to add the Java client library dependency for Aeropike in the Maven project. The following dependencies can be added to the 'pom. xml' file:
<dependencies>
<dependency>
<groupId>com.aerospike</groupId>
<artifactId>aerospike-client</artifactId>
<version>4.7.0</version>
</dependency>
</dependencies>
Please note that the specific version number may vary, and you can adjust it according to the actual situation.
These sample codes only demonstrate how to use Aerospike's aggregation functions for querying, and you can make changes and extensions according to your own needs.
