Cassandra DataStax: Developer Guide With Spring Data Cassandra

• http://www.datastax.com/documentation/cassandra/2.0/cassandra/gettingStartedCassandraIntro.html
• Recommended stable production version — DataStax Enterprise 4.5. (When this article was written).
• Compound Partition and Clustered keys: http://www.datastax.com/documentation/cql/3.0/cql/ddl/ddl_compound_keys_c.html
• Spring-Data-Cassandra API and reference docs: http://projects.spring.io/spring-data-cassandra/

Download and Installation

1. Tarball Installation

DataStax DB

• You need to register yourself with DataStax for the download.
• DataStax Enterprise — http://www.datastax.com/download#dl-enterprise.
• Create these folders and permissions:

mkdir -p /var/log/cassandrasudo
sudo chmod 777 /var/log/cassandrasudo

mkdir -p /var/lib/cassandra/datasudo
chmod 777 /var/lib/cassandra/datasudo

mkdir -p /var/lib/cassandra/commitlogsudo
chmod 777 /var/lib/cassandra/commitlogsudo

mkdir -p /var/lib/cassandra/saved_cachessudo
chmod 777 /var/lib/cassandra/saved_caches

• How to run Cassandra: Go to the DataStax Cassandra installed folder on Mac/Linux/Unix env:

  cd /Users/<userName>/dse-<version>/bin
  sudo ./dse cassandra -f
  
  //This above command Cassandra DB on your local system. Hit enter to quit from ruining server in background and start CQL query console.
  sudo ./cqlsh

Create Schema:

CREATE SCHEMA event_owner WITH replication = {‘class’: ‘SimpleStrategy’, ‘replication_factor’ : 1 };

1. Schema(Keyspace) name: event_owner
2. Table name: event_audit

Table creation syntax: Please find the revised data model and details below.

Note: I have used expanded names for easier understanding, which can be shortened later on.

CREATE TABLE  event_owner.event_audit (
ctg    text,
month       timestamp,
ctgid      text,
ver     timeuuid,
userid      text,
action      text,
content     text,
PRIMARY KEY ((category,month),cat_id,version)
) WITH CLUSTERING ORDER BY (cat_id ASC, version DESC);

Sample Data

Description

• category
  • Commitcode/Part Association/EventTag [CC / PA / ET]
• month
  • 12 AM timestamp of the first day of the month the change is made
• cat_id
  • Unique id for a particular category [Say inc axe of commit code it is cc_id say 9000]
• version
  • it is the unique id that indicates the version number.
  • You can populate it using now() function.
  • It has an embedded timestamp that can be used to know the timestamp. Use dateOf() function to get the timestamp value.
• user id
  • id of the user who made the change
• action
  • SAVE DRAFT, PUBLISH, DELETE, etc.
• content
  • actual JSON content after the change [full json]

Sample Query to Access the Data

cqlsh:cdb> select * from audit where category=’CC’ and month=’2014-01-01 05:30:00+0530′ and cat_id=’9000′;

SQL Like Commands: You can use same standard SQL DDL/DML commands/syntax for Cassandra query:

• Drop table
• Update
• Delete
• Truncate
• Select query

2. DataStax OpsCenter:

http://www.datastax.com/what-we-offer/products-services/datastax-opscenter

3. DataStax DevCenter:

Installation: DataStax DevCenter is a visual CQL query tool for Cassandra and DataStax Enterprise.

How to start OpsCenter GUI:

http://www.datastax.com/documentation/getting_started/doc/getting_started/gettingStartedInstallOpscTar_t.html

2. Package Installation:

DataStax All-in-One Installer

• You need to register with DataStax for DataStax All-in-One Installer download.
• DataStax Enterprise — http://www.datastax.com/download#dl-dseinstaller
• Installation: http://www.datastax.com/documentation/getting_started/doc/getting_started/gsInstallNonRoot.html
• Follow the installation steps given in above link and install.
• Once your Installation is completed, your DataStax will be in the following location:

/users/dse

How to Run DataStax?

• Cassandra: Go to your /Users/dse via Terminal and execute the following command. This will start Cassandra.

sudo ./bin/dse cassandra -f

Opscenter and DataStax-Agent:

• Go to /Users//dse in new Tab and execute the command. This will start the opscenter

  sudo ./opscenter/bin/opscenter -f 

• Go to /Users//dse in new Tab and execute the command. This will start the datastax-agent

  sudo ./datastax-agent/bin/datastax-agent -f

Using DataStax:

• Now you can see the Opscenter in Browser in the following address: localhost:8888/
• Here, you are able to see your Cassandra cluster visually (kind of a monitoring tool for Cassandra).
• You need to start DevCenter — which came with DataStax (you can find the shortcut for DevCenter in your Desktop), if you want to query and access the cassandra DB.
• Getting Started with DevCenter: http://www.datastax.com/what-we-offer/products-services/devcenter

Integrate Cassandra With Spring Data Cassandra:

/**
 * Created by: Rajiv Srivastava
 */
@Configuration
@ComponentScan(basePackages = {com.cassandraproject.dao,com.cassandraproject.utils})
@EnableCassandraRepositories(basePackages ={com.cassandraproject.repository})
public class AuditCoreContextConfig extends AbstractCassandraConfiguration {

 @Override
 protected String getKeyspaceName() {
 return event_owner; //Schema or Keyspace name
 }

 @Override
 protected String getContactPoints() {
 return localhost;//IP address of server/local machine. Host of a clusters can be separated with comma (,) like host1,host2. Also minimum two host should be added, so that second Cassandra server will be connected if first is down.
 }

 @Override
 protected int getPort() {
 return 9042; //Cassandra DB port
 }
}

3. Data Modeling

a. Primary/Clustered/Partitioned key

/**
 * Created by: Rajiv Srivastava
 */

/* Keyspac/Schema- event_owner
 * CREATE TABLE event_owner.event_audit (
 ctg text,
 month timestamp,
 ctgid text,
 ver timeuuid,
 userid text,
 action text,
 content text,
 PRIMARY KEY ((ctg,month),ctgid,ver)
 )WITH CLUSTERING ORDER BY (ctgid ASC, ver DESC);

*/

@PrimaryKeyClass
public class EventAuditKey implements Serializable {

private static final long serialVersionUID = 1L;

@PrimaryKeyColumn(name = ctg, ordinal = 0, type = PrimaryKeyType.PARTITIONED)
 private String category;

 @PrimaryKeyColumn(name = month, ordinal = 1, type = PrimaryKeyType.PARTITIONED)
 private Date month;

 @PrimaryKeyColumn(name = ctgid, ordinal = 2, type = PrimaryKeyType.CLUSTERED, ordering =Ordering.ASCENDING)
 private String categoryId;

 @PrimaryKeyColumn(name = ver, ordinal = 3, type = PrimaryKeyType.CLUSTERED, ordering = Ordering.DESCENDING)
 private UUID version;

b. Repository

/**
 * Created by: Rajiv Srivastava*/
@Repository
public interface AuditRepository extends CrudRepository <EventAudit, EventAuditKey> {

@Query(select * from event_owner.event_audit)
public List<EventAudit&amp> eventAudit();
}

c. CRUD Operation Using JPA/CrudRepository — DAO Layer

/**
 * Created by: Rajiv Srivastava*/
@Component
public class EventDaoImpl implements EventAuditDao {

 @Autowired
 public AuditRepository auditRepository;

 @Override
 public void save(EventAudit entity) {
 auditRepository.save(entity);

 }

 @Override
 public void save(Collection<EventAudit> entities) {
 auditRepository.save(entities);
 }

 @Override
 public EventAudit find(EventAuditKey eventAuditKey) {
 if(null==eventAuditKey){
 throw new IllegalArgumentException(It doesn't has all required instance variable set);
 }
 return auditRepository.findOne(eventAuditKey);
 }

 @Override
 public List<EventAudit> getAll() {

 Iterable<EventAudit> iterable=auditRepository.findAll();
 if(null != iterable.iterator()){
 return Lists.newArrayList(iterable.iterator());
 }
 return new ArrayList<>();
 }

 @Override
 public List<EventAudit> getListEventAuditMonthCategoryWise(Date date, String Category) {
 // TODO Auto-generated method stub
 return null;
 }
}

Join us in #cassandra on irc.freenode.net and ask questions.

For more on what commands are supported by CQL, see https://github.com/apache/cassandra/blob/trunk/doc/cql3/CQL.textile. A reasonable way to think of it is as “SQL minus joins and subqueries.”