4. Cassandra support

The Cassandra support contains a wide range of features which are summarized below.

For most tasks you will find yourself using CassandraTemplate or the Repository support that both leverage the rich mapping functionality. CassandraTemplate is the place to look for accessing functionality such as incrementing counters or ad-hoc CRUD operations. CassandraTemplate also provides callback methods so that it is easy for you to get a hold of the low level API artifacts such as com.datastax.driver.core.Session to communicate directly with Cassandra. The goal with naming conventions on various API artifacts is to copy those in the base DataStax Java driver so you can easily map your existing knowledge onto the Spring APIs.

4.1 Getting Started

Spring Data Cassandra uses the DataStax Java Driver version 2.X, which supports DataStax Enterprise 4/Cassandra 2.0, and Java SE 6 or higher. The latest commercial release (2.X as of this writing) is recommended. An easy way to bootstrap setting up a working environment is to create a Spring based project in STS.

First you need to set up a running Cassandra server.

To create a Spring project in STS go to File -> New -> Spring Template Project -> Simple Spring Utility Project -> press Yes when prompted. Then enter a project and a package name such as org.spring.cassandra.example.

Then add the following to pom.xml dependencies section.

<dependencies>

  <!-- other dependency elements omitted -->

  <dependency>
    <groupId>org.springframework.data</groupId>
    <artifactId>spring-data-cassandra</artifactId>
    <version>1.0.0.RELEASE</version>
  </dependency>

</dependencies>

Also change the version of Spring in the pom.xml to be

<spring.framework.version>3.2.8.RELEASE</spring.framework.version>

You will also need to add the location of the Spring Milestone repository for maven to your pom.xml which is at the same level of your <dependencies/> element

<repositories>
  <repository>
    <id>spring-milestone</id>
    <name>Spring Maven MILESTONE Repository</name>
    <url>http://repo.spring.io/libs-milestone</url>
  </repository>
</repositories>

The repository is also browseable here.

Create a simple Employee class to persist.

package org.spring.cassandra.example; 
 
import org.springframework.data.cassandra.mapping.PrimaryKey; 
import org.springframework.data.cassandra.mapping.Table; 
 
@Table 
public class Person { 
 
 @PrimaryKey 
 private String id; 
 
 private String name; 
 private int age; 
 
 public Person(String id, String name, int age) { 
  this.id = id; 
  this.name = name; 
  this.age = age; 
 } 
 
 public String getId() { 
  return id; 
 } 
 
 public String getName() { 
  return name; 
 } 
 
 public int getAge() { 
  return age; 
 } 
 
 @Override 
 public String toString() { 
  return "Person [id=" + id + ", name=" + name + ", age=" + age + "]"; 
 } 
 
}

And a main application to run

package org.spring.cassandra.example; 
 
import java.net.InetAddress; 
import java.net.UnknownHostException; 
 
import org.slf4j.Logger; 
import org.slf4j.LoggerFactory; 
import org.springframework.data.cassandra.core.CassandraOperations; 
import org.springframework.data.cassandra.core.CassandraTemplate; 
 
import com.datastax.driver.core.Cluster; 
import com.datastax.driver.core.Session; 
import com.datastax.driver.core.querybuilder.QueryBuilder; 
import com.datastax.driver.core.querybuilder.Select; 
 
public class CassandraApp { 
 
 private static final Logger LOG = LoggerFactory.getLogger(CassandraApp.class); 
 
 private static Cluster cluster; 
 private static Session session; 
 
 public static void main(String[] args) { 
 
  try { 
 
   cluster = Cluster.builder().addContactPoints(InetAddress.getLocalHost()).build(); 
 
   session = cluster.connect("mykeyspace"); 
 
   CassandraOperations cassandraOps = new CassandraTemplate(session); 
 
   cassandraOps.insert(new Person("1234567890", "David", 40)); 
 
   Select s = QueryBuilder.select().from("person"); 
   s.where(QueryBuilder.eq("id", "1234567890")); 
 
   LOG.info(cassandraOps.queryForObject(s, Person.class).getId()); 
 
   cassandraOps.truncate("person"); 
 
  } catch (UnknownHostException e) { 
   e.printStackTrace(); 
  } 
 
 } 
} 

Even in this simple example, there are a few things to observe.

  • You can create an instance of CassandraTemplate with a Cassandra Session, derived from the Cluster.

  • You must annotate your POJO as a Cassandra @Table, and also annotate the @PrimaryKey. Optionally you can override these mapping names to match your Cassandra database table and column names.

  • You can use CQL String, or the DataStax QueryBuilder to construct you queries.

4.2 Examples Repository

After the initial release of Spring Data Cassandra 1.0.0, we will start working on a showcase repository with full examples.

4.3 Connecting to Cassandra with Spring

4.3.1 Externalize Connection Properties

Create a properties file with the information you need to connect to Cassandra. The contact points are keyspace are the minimal required fields, but port is added here for clarity.

We will call this cassandra.properties

cassandra.contactpoints=10.1.55.80,10.1.55.81
cassandra.port=9042
cassandra.keyspace=showcase

We will use spring to load these properties into the Spring Context in the next two examples.

4.3.2 XML Configuration

The XML Configuration elements for a basic Cassandra configuration are shown below. These elements all use default bean names to keep the configuration code clean and readable.

While this example show how easy it is to configure Spring to connect to Cassandra, there are many other options. Basically, any option available with the DataStax Java Driver is also available in the Spring Data Cassandra configuration. This is including, but not limited to Authentication, Load Balancing Policies, Retry Policies and Pooling Options. All of the Spring Data Cassandra method names and XML elements are named exactly (or as close as possible) like the configuration options on the driver so mapping any existing driver configuration should be straight forward.

<?xml version='1.0'?>
<beans xmlns="http://www.springframework.org/schema/beans"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:cassandra="http://www.springframework.org/schema/data/cassandra"
  xmlns:context="http://www.springframework.org/schema/context"
  xsi:schemaLocation="http://www.springframework.org/schema/cql http://www.springframework.org/schema/cql/spring-cql-1.0.xsd
    http://www.springframework.org/schema/data/cassandra http://www.springframework.org/schema/data/cassandra/spring-cassandra-1.0.xsd
    http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
    http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.2.xsd">

  <!-- Loads the properties into the Spring Context and uses them to fill 
    in placeholders in the bean definitions -->
  <context:property-placeholder location="classpath:cassandra.properties" />

  <!-- REQUIRED: The Cassandra Cluster -->
  <cassandra:cluster contact-points="${cassandra.contactpoints}"
    port="${cassandra.port}" />

  <!-- REQUIRED: The Cassandra Session, built from the Cluster, and attaching 
    to a keyspace -->
  <cassandra:session keyspace-name="${cassandra.keyspace}" />

  <!-- REQUIRED: The Default Cassandra Mapping Context used by CassandraConverter -->
  <cassandra:mapping />

  <!-- REQUIRED: The Default Cassandra Converter used by CassandraTemplate -->
  <cassandra:converter />

  <!-- REQUIRED: The Cassandra Template is the building block of all Spring 
    Data Cassandra -->
  <cassandra:template id="cassandraTemplate" />

  <!-- OPTIONAL: If you are using Spring Data Cassandra Repositories, add 
    your base packages to scan here -->
  <cassandra:repositories base-package="org.spring.cassandra.example.repo" />

</beans>

4.3.3 Java Configuration

The following class show a basic and minimal Cassandra configuration using the AnnotationConfigApplicationContext (aka JavaConfig).

package org.spring.cassandra.example.config;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;
import org.springframework.core.env.Environment;
import org.springframework.data.cassandra.config.CassandraClusterFactoryBean;
import org.springframework.data.cassandra.config.CassandraSessionFactoryBean;
import org.springframework.data.cassandra.config.SchemaAction;
import org.springframework.data.cassandra.convert.CassandraConverter;
import org.springframework.data.cassandra.convert.MappingCassandraConverter;
import org.springframework.data.cassandra.core.CassandraOperations;
import org.springframework.data.cassandra.core.CassandraTemplate;
import org.springframework.data.cassandra.mapping.BasicCassandraMappingContext;
import org.springframework.data.cassandra.mapping.CassandraMappingContext;
import org.springframework.data.cassandra.repository.config.EnableCassandraRepositories;

@Configuration
@PropertySource(value = { "classpath:cassandra.properties" })
@EnableCassandraRepositories(basePackages = { "org.spring.cassandra.example.repo" })
public class CassandraConfig {

  private static final Logger LOG = LoggerFactory.getLogger(CassandraConfig.class);

  @Autowired
  private Environment env;

  @Bean
  public CassandraClusterFactoryBean cluster() {

    CassandraClusterFactoryBean cluster = new CassandraClusterFactoryBean();
    cluster.setContactPoints(env.getProperty("cassandra.contactpoints"));
    cluster.setPort(Integer.parseInt(env.getProperty("cassandra.port")));

    return cluster;
  }

  @Bean
  public CassandraMappingContext mappingContext() {
    return new BasicCassandraMappingContext();
  }

  @Bean
  public CassandraConverter converter() {
    return new MappingCassandraConverter(mappingContext());
  }

  @Bean
  public CassandraSessionFactoryBean session() throws Exception {

    CassandraSessionFactoryBean session = new CassandraSessionFactoryBean();
    session.setCluster(cluster().getObject());
    session.setKeyspaceName(env.getProperty("cassandra.keyspace"));
    session.setConverter(converter());
    session.setSchemaAction(SchemaAction.NONE);

    return session;
  }

  @Bean
  public CassandraOperations cassandraTemplate() throws Exception {
    return new CassandraTemplate(session().getObject());
  }
}

4.4 General auditing configuration

Auditing support is not available in the current version.

4.5 Introduction to CassandraTemplate

4.5.1 Instantiating CassandraTemplate

CassandraTemplate should always be configured as a Spring Bean, although we show an example above where you can instantiate it directly. But for the purposes of this being a Spring module, lets assume we are using the Spring Container.

CassandraTemplate is an implementation of CassandraOperations. You should always assign your CassandraTemplate to its interface definition, CassandraOperations.

There are 2 easy ways to get a CassandraTemplate, depending on how you load you Spring Application Context.

AutoWiring

@Autowired
private CassandraOperations cassandraOperations;

Like all Spring Autowiring, this assumes there is only one bean of type CassandraOperations in the ApplicationContext. If you have multiple CassandraTemplate beans (which will be the case if you are working with multiple keyspaces in the same project), use the @Qualifier annotation to designate which bean you want to Autowire.

@Autowired
@Qualifier("myTemplateBeanId")
private CassandraOperations cassandraOperations;

Bean Lookup with ApplicationContext

You can also just lookup the CassandraTemplate bean from the ApplicationContext.

CassandraOperations cassandraOperations = applicationContext.getBean("cassandraTemplate", CassandraOperations.class);

4.6 Saving, Updating, and Removing Rows

CassandraTemplate provides a simple way for you to save, update, and delete your domain objects and map those objects to documents stored in Cassandra.

4.6.1 How the Composite Primary Key fields are handled in the mapping layer

Cassandra requires that you have at least 1 Partition Key field for a CQL Table. Alternately, you can have one or more Clustering Key fields. When your CQL Table has a composite Primary Key field you must create a @PrimaryKeyClass to define the structure of the composite PK. In this context, composite PK means one or more partition columns, or 1 partition column plus one or more clustering columns.

Simplest Composite Key

The simplest for of a Composite key is a key with one partition key and one clustering key. Here is an example of a CQL Table, and the corresponding POJOs that represent the table and it's composite key.

CQL Table defined in Cassandra

create table login_event(
  person_id text, 
  event_time timestamp,
  event_code int,
  ip_address text,
  primary key (person_id, event_time))
  with CLUSTERING ORDER BY (event_time DESC)
;

Class defining the Composite Primary Key. NOTE: PrimaryKeyClass must implement Serializable and provide implementation of hashCode() and equals() just like the example.

package org.spring.cassandra.example;

import java.io.Serializable;
import java.util.Date;

import org.springframework.cassandra.core.Ordering;
import org.springframework.cassandra.core.PrimaryKeyType;
import org.springframework.data.cassandra.mapping.PrimaryKeyClass;
import org.springframework.data.cassandra.mapping.PrimaryKeyColumn;

@PrimaryKeyClass
public class LoginEventKey implements Serializable {

  @PrimaryKeyColumn(name = "person_id", ordinal = 0, type = PrimaryKeyType.PARTITIONED)
  private String personId;

  @PrimaryKeyColumn(name = "event_time", ordinal = 1, type = PrimaryKeyType.CLUSTERED, ordering = Ordering.DESCENDING)
  private Date eventTime;

  public String getPersonId() {
    return personId;
  }

  public void setPersonId(String personId) {
    this.personId = personId;
  }

  public Date getEventTime() {
    return eventTime;
  }

  public void setEventTime(Date eventTime) {
    this.eventTime = eventTime;
  }

  @Override
  public int hashCode() {
    final int prime = 31;
    int result = 1;
    result = prime * result + ((eventTime == null) ? 0 : eventTime.hashCode());
    result = prime * result + ((personId == null) ? 0 : personId.hashCode());
    return result;
  }

  @Override
  public boolean equals(Object obj) {
    if (this == obj)
      return true;
    if (obj == null)
      return false;
    if (getClass() != obj.getClass())
      return false;
    LoginEventKey other = (LoginEventKey) obj;
    if (eventTime == null) {
      if (other.eventTime != null)
        return false;
    } else if (!eventTime.equals(other.eventTime))
      return false;
    if (personId == null) {
      if (other.personId != null)
        return false;
    } else if (!personId.equals(other.personId))
      return false;
    return true;
  }
}

Class defining the CQL Table, having the Composite Primary Key as an attribute and annotated as the PrimaryKey.

package org.spring.cassandra.example;

import org.springframework.data.cassandra.mapping.Column;
import org.springframework.data.cassandra.mapping.PrimaryKey;
import org.springframework.data.cassandra.mapping.Table;

@Table(value = "login_event")
public class LoginEvent {

  @PrimaryKey
  private LoginEventKey pk;

  @Column(value = "event_code")
  private int eventCode;

  @Column(value = "ip_address")
  private String ipAddress;

  public LoginEventKey getPk() {
    return pk;
  }

  public void setPk(LoginEventKey pk) {
    this.pk = pk;
  }

  public int getEventCode() {
    return eventCode;
  }

  public void setEventCode(int eventCode) {
    this.eventCode = eventCode;
  }

  public String getIpAddress() {
    return ipAddress;
  }

  public void setIpAddress(String ipAddress) {
    this.ipAddress = ipAddress;
  }

}

Complex Composite Primary Key

The annotations provided with Spring Data Cassandra can handle any key combination available in Cassandra. Here is one more example of a Composite Primary Key with 5 columns, 2 of which are a composite partition key, and the remaining 3 are ordered clustering keys. The getters/setters, hashCode and equals are omitted for brevity.

package org.spring.cassandra.example;

import java.io.Serializable;
import java.util.Date;

import org.springframework.cassandra.core.Ordering;
import org.springframework.cassandra.core.PrimaryKeyType;
import org.springframework.data.cassandra.mapping.PrimaryKeyClass;
import org.springframework.data.cassandra.mapping.PrimaryKeyColumn;

@PrimaryKeyClass
public class DetailedLoginEventKey implements Serializable {

  @PrimaryKeyColumn(name = "person_id", ordinal = 0, type = PrimaryKeyType.PARTITIONED)
  private String personId;

  @PrimaryKeyColumn(name = "wks_id", ordinal = 1, type = PrimaryKeyType.PARTITIONED)
  private String workstationId;

  @PrimaryKeyColumn(ordinal = 2, type = PrimaryKeyType.CLUSTERED, ordering = Ordering.ASCENDING)
  private Date application;

  @PrimaryKeyColumn(name = "event_code", ordinal = 3, type = PrimaryKeyType.CLUSTERED, ordering = Ordering.ASCENDING)
  private Date eventCode;

  @PrimaryKeyColumn(name = "event_time", ordinal = 4, type = PrimaryKeyType.CLUSTERED, ordering = Ordering.DESCENDING)
  private Date eventTime;

  ...

}

4.6.2 Type mapping

Spring Data Cassandra relies on the DataStax Java Driver type mapping component. This approach ensures that as types are added or changed, the Spring Data Cassandra module will continue to function without requiring changes. For more information on the DataStax CQL3 to Java Type mappings, please see their Documentation here.

4.6.3 Methods for saving and inserting rows

Single records inserts

To insert one row at a time, there are many options. At this point you should already have a cassandraTemplate available to you so we will just how the relevant code for each section, omitting the template setup.

Insert a record with an annotated POJO.

cassandraOperations.insert(new Person("123123123", "Alison", 39));

Insert a row using the QueryBuilder.Insert object that is part of the DataStax Java Driver.

Insert insert = QueryBuilder.insertInto("person");
insert.setConsistencyLevel(ConsistencyLevel.ONE);
insert.value("id", "123123123");
insert.value("name", "Alison");
insert.value("age", 39);

cassandraOperations.execute(insert);

Then there is always the old fashioned way. You can write your own CQL statements.

String cql = "insert into person (id, name, age) values ('123123123', 'Alison', 39)";
   
cassandraOperations.execute(cql);

Multiple inserts for high speed ingestion

CQLOperations, which is extended by CassandraOperations is a lower level Template that you can use for just about anything you need to accomplish with Cassandra. CqlOperations includes several overloaded methods named ingest().

Use these methods to pass a CQL String with Bind Markers, and your preferred flavor of data set (Object[][] and List<List<T>>).

The ingest method takes advantage of static PreparedStatements that are only prepared once for performance. Each record in your data list is bound to the same PreparedStatement, then executed asynchronously for high performance.

    String cqlIngest = "insert into person (id, name, age) values (?, ?, ?)";

    List<Object> person1 = new ArrayList<Object>();
    person1.add("10000");
    person1.add("David");
    person1.add(40);

    List<Object> person2 = new ArrayList<Object>();
    person2.add("10001");
    person2.add("Roger");
    person2.add(65);

    List<List<?>> people = new ArrayList<List<?>>();
    people.add(person1);
    people.add(person2);

    cassandraOperations.ingest(cqlIngest, people);

4.6.4 Updating rows in a CQL table

Much like inserting, there are several flavors of update from which you can choose.

Update a record with an annotated POJO.

cassandraOperations.update(new Person("123123123", "Alison", 35));

Update a row using the QueryBuilder.Update object that is part of the DataStax Java Driver.

Update update = QueryBuilder.update("person");
update.setConsistencyLevel(ConsistencyLevel.ONE);
update.with(QueryBuilder.set("age", 35));
update.where(QueryBuilder.eq("id", "123123123"));

cassandraOperations.execute(update);

Then there is always the old fashioned way. You can write your own CQL statements.

String cql = "update person set age = 35 where id = '123123123'";

cassandraOperations.execute(cql);

4.6.5 Methods for removing rows

Much like inserting, there are several flavors of delete from which you can choose.

Delete a record with an annotated POJO.

cassandraOperations.delete(new Person("123123123", null, 0));

Delete a row using the QueryBuilder.Delete object that is part of the DataStax Java Driver.

Delete delete = QueryBuilder.delete().from("person");
delete.where(QueryBuilder.eq("id", "123123123"));

cassandraOperations.execute(delete);

Then there is always the old fashioned way. You can write your own CQL statements.

String cql = "delete from person where id = '123123123'";

cassandraOperations.execute(cql);

4.6.6 Methods for truncating tables

Much like inserting, there are several flavors of truncate from which you can choose.

Truncate a table using the truncate() method.

cassandraOperations.truncate("person");

Truncate a table using the QueryBuilder.Truncate object that is part of the DataStax Java Driver.

Truncate truncate = QueryBuilder.truncate("person");

cassandraOperations.execute(truncate);

Then there is always the old fashioned way. You can write your own CQL statements.

String cql = "truncate person";

cassandraOperations.execute(cql);

4.7 Querying CQL Tables

Tthere are several flavors of select and query from which you can choose. Please see the CassandraTemplate API documentation for all overloads available.

Query a table for multiple rows and map the results to a POJO.

String cqlAll = "select * from person";

List<Person> results = cassandraOperations.select(cqlAll, Person.class);
for (Person p : results) {
	LOG.info(String.format("Found People with Name [%s] for id [%s]", p.getName(), p.getId()));
}

Query a table for a single row and map the result to a POJO.

String cqlOne = "select * from person where id = '123123123'";

Person p = cassandraOperations.selectOne(cqlOne, Person.class);
LOG.info(String.format("Found Person with Name [%s] for id [%s]", p.getName(), p.getId()));

Query a table using the QueryBuilder.Select object that is part of the DataStax Java Driver.

Select select = QueryBuilder.select().from("person");
select.where(QueryBuilder.eq("id", "123123123"));

Person p = cassandraOperations.selectOne(select, Person.class);
LOG.info(String.format("Found Person with Name [%s] for id [%s]", p.getName(), p.getId()));

Then there is always the old fashioned way. You can write your own CQL statements, and there are several callback handlers for mapping the results. The example uses the RowMapper interface.

String cqlAll = "select * from person";
List<Person> results = cassandraOperations.query(cqlAll, new RowMapper<Person>() {

	public Person mapRow(Row row, int rowNum) throws DriverException {
		Person p = new Person(row.getString("id"), row.getString("name"), row.getInt("age"));
		return p;
	}
});

for (Person p : results) {
	LOG.info(String.format("Found People with Name [%s] for id [%s]", p.getName(), p.getId()));
}

4.8 Overriding default mapping with custom converters

In order to have more fine grained control over the mapping process you can register Spring converters with the CassandraConverter implementations such as the MappingCassandraConverter.

The MappingCassandraConverter checks to see if there are any Spring converters that can handle a specific class before attempting to map the object itself. To 'hijack' the normal mapping strategies of the MappingCassandraConverter, perhaps for increased performance or other custom mapping needs, you first need to create an implementation of the Spring Converter interface and then register it with the MappingConverter.

[Note]Note

For more information on the Spring type conversion service see the reference docs here.

4.8.1 Saving using a registered Spring Converter

Coming Soon!

4.8.2 Reading using a Spring Converter

Coming Soon!

4.8.3 Registering Spring Converters with the CassandraConverter

Coming Soon!

4.8.4 Converter disambiguation

Coming Soon!

4.9 Executing Commands

4.9.1 Methods for executing commands

The CassandraTemplate has many overloads for execute() and executeAsync(). Pass in the CQL command you wish to be executed, and handle the appropriate response.

This example uses the basic AsynchronousQueryListener that comes with Spring Data Cassandra. Please see the API documentation for all the options. There should be nothing you cannot perform in Cassandra with the execute() and executeAsync() methods.

cassandraOperations.executeAsynchronously("delete from person where id = '123123123'",
		new AsynchronousQueryListener() {

			public void onQueryComplete(ResultSetFuture rsf) {
				LOG.info("Async Query Completed");
			}
		});

This example shows how to create and drop a table, using different API objects, all passed to the execute() methods.

cassandraOperations.execute("create table test_table (id uuid primary key, event text)");

DropTableSpecification dropper = DropTableSpecification.dropTable("test_table");
cassandraOperations.execute(dropper);

4.10 Exception Translation

The Spring framework provides exception translation for a wide variety of database and mapping technologies. This has traditionally been for JDBC and JPA. The Spring support for Cassandra extends this feature to the Cassandra Database by providing an implementation of the org.springframework.dao.support.PersistenceExceptionTranslator interface.

The motivation behind mapping to Spring's consistent data access exception hierarchy is that you are then able to write portable and descriptive exception handling code without resorting to coding against Cassandra Exceptions. All of Spring's data access exceptions are inherited from the root DataAccessException class so you can be sure that you will be able to catch all database related exception within a single try-catch block.