Implementing IBM Cloudant aggregation queries using Java
To implement aggregate queries for IBM Cloudant using Java, you first need to add the following dependent Maven coordinates:
<dependency>
<groupId>com.ibm.cloud</groupId>
<artifactId>cloudant</artifactId>
<version>10.10.1</version>
</dependency>
Then, the following example Java code can be used to implement various data aggregation queries:
1. Count the total number of documents:
import com.cloudant.client.api.ClientBuilder;
import com.cloudant.client.api.CloudantClient;
public class AggregateQueriesExample {
public static void main(String[] args) {
CloudantClient client = ClientBuilder.account("USERNAME")
.username("USERNAME")
.password("PASSWORD")
.build();
long totalDocuments = client.database("DATABASE_NAME").info().getDocCount();
System.out.println("Total Documents: " + totalDocuments);
}
}
2. Sum aggregation query:
import com.cloudant.client.api.ClientBuilder;
import com.cloudant.client.api.CloudantClient;
import com.cloudant.client.api.Database;
import com.cloudant.client.api.model.FindByIndexOptions;
import com.cloudant.client.org.lightcouch.NoDocumentException;
import com.cloudant.client.org.lightcouch.View;
public class AggregateQueriesExample {
public static void main(String[] args) {
CloudantClient client = ClientBuilder.account("USERNAME")
.username("USERNAME")
.password("PASSWORD")
.build();
Database database = client.database("DATABASE_NAME", false);
View view = database.getViewRequestBuilder("DESIGN_DOC_NAME", "VIEW_NAME")
.newFindByIndexOptions()
.reduce(true)
.build();
try {
double sum = (Double) view.getResponse().getRows().get(0).getValue();
System.out.println("Sum: " + sum);
} catch (NoDocumentException e) {
System.out.println("No documents found for the view.");
}
}
}
3. Average aggregation query:
import com.cloudant.client.api.ClientBuilder;
import com.cloudant.client.api.CloudantClient;
import com.cloudant.client.api.Database;
import com.cloudant.client.api.model.FindByIndexOptions;
import com.cloudant.client.org.lightcouch.NoDocumentException;
import com.cloudant.client.org.lightcouch.View;
public class AggregateQueriesExample {
public static void main(String[] args) {
CloudantClient client = ClientBuilder.account("USERNAME")
.username("USERNAME")
.password("PASSWORD")
.build();
Database database = client.database("DATABASE_NAME", false);
View view = database.getViewRequestBuilder("DESIGN_DOC_NAME", "VIEW_NAME")
.newFindByIndexOptions()
.reduce(true)
.build();
try {
double average = (Double) view.getResponse().getRows().get(0).getValue();
System.out.println("Average: " + average);
} catch (NoDocumentException e) {
System.out.println("No documents found for the view.");
}
}
}
4. Maximum aggregation query:
import com.cloudant.client.api.ClientBuilder;
import com.cloudant.client.api.CloudantClient;
import com.cloudant.client.api.Database;
import com.cloudant.client.api.model.FindByIndexOptions;
import com.cloudant.client.org.lightcouch.NoDocumentException;
import com.cloudant.client.org.lightcouch.View;
public class AggregateQueriesExample {
public static void main(String[] args) {
CloudantClient client = ClientBuilder.account("USERNAME")
.username("USERNAME")
.password("PASSWORD")
.build();
Database database = client.database("DATABASE_NAME", false);
View view = database.getViewRequestBuilder("DESIGN_DOC_NAME", "VIEW_NAME")
.newFindByIndexOptions()
.reduce(true)
.build();
try {
double max = (Double) view.getResponse().getRows().get(0).getValue();
System.out.println("Maximum: " + max);
} catch (NoDocumentException e) {
System.out.println("No documents found for the view.");
}
}
}
The 'USERNAME' and 'PASSWORD' in these sample codes should be replaced with the correct IBM Cloudant credential information, and the 'DATABASE-NAME' should be replaced with the name of the database to be aggregated for the query. At the same time, "DESIGN_DOC_NAME" and "VIEW_NAME" need to be replaced with the actual Software design description and view name.
Please note that the design and view of the actual aggregated query need to be set up on the IBM Cloudant web interface. These example codes only demonstrate how to execute aggregate queries.
