Cassandra with Spring data

AWS keyspace 에 데이터 베이스 생성하기

use kspc_test;

create table kspc_test.event (
  type text,
  target_idx bigint,
  target_type tinyint,
  source text,
  send_time timestamp,
  ext_data text,
  primary key (target_idx, send_time)
) WITH CLUSTERING ORDER BY (send_time DESC);

• primary key 에 등록한 키값으로 유니크 값을 만들고 이 값에 따라 카산드라 디비에 저장되고 복제됨
• Clustering 에 미리 order by를 지정해 주지않으면 select 쿼리 문에서 사용할 수 없음

Insert Row

CassandraRepository

https://docs.spring.io/spring-data/cassandra/docs/current/reference/html/#repositories.definition-tuning

package org.springframework.data.cassandra.repository;

@NoRepositoryBean
public interface CassandraRepository<T, ID> extends CrudRepository<T, ID> {
	<S extends T> S insert(S entity);
	<S extends T> List<S> insert(Iterable<S> entities);
}

interface UserRepository extends CassandraRepository<User, Long> {
  User save(User user);
}

CassandraOperaions / CassandraTemplate

https://docs.spring.io/spring-data/cassandra/docs/current/reference/html/#cassandra.template.insert-update

Person bob = new Person("Bob", 33);
cassandraTemplate.insert(bob);

Select Row

CassandraRepository

https://docs.spring.io/spring-data/cassandra/docs/current/reference/html/#repositories

• CrudRepository를 확장해서 사용하는 방법 (JPA를 사용하는 방법과 유사하다)

  public interface CrudRepository<T, ID> extends Repository<T, ID> {
  
    <S extends T> S save(S entity);        // Saves the given entity.
  
    Optional<T> findById(ID primaryKey);   // Returns the entity identified by the given ID.
  
    Iterable<T> findAll();                 // Returns all entities.
  
    long count();                        
  
    void delete(T entity);               
  
    boolean existsById(ID primaryKey);   
  
    // … more functionality omitted.
  }

• Cassandra repository supports Spring Data Repository (less boilerplate code to implement data access layers) https://docs.spring.io/spring-data/cassandra/docs/current/reference/html/#repositories
• CassandraPageRequest.of(page, limit, sort)  because classic paging patterns using limit/offset are not applicable to Cassandra.
• keywords for query methods https://docs.spring.io/spring-data/cassandra/docs/current/reference/html/#cassandra.repositories.queries

@Repository
public interface MsgCassandraRepository extends CassandraRepository<ChatMsg, MsgKey> {

    Slice<ChatMsg> findByDestTypeAndDestAndMsgIdxIsLessThanEqual(byte destType, String dest, long startMsgIdx, CassandraPageRequest msg_idx);
}

CqlTemplate

https://docs.spring.io/spring-data/cassandra/docs/current/reference/html/#cassandra.cql-template

foundational building block for CassandraTemplate

int countOfActorsNamedJoe = cqlTemplate.queryForObject(
    "SELECT COUNT(*) FROM t_actor WHERE first_name = ?", Integer.class, "Joe");

CassandraOperaions / CassandraTemplate

• Once configured, CassandraTemplate is thread-safe and can be reused across multiple instances.
• CassandraOperations를 가지고 cql 또는 query object 대신 도메인 오브젝트를 전달

https://docs.spring.io/spring-data/cassandra/docs/current/reference/html/#cassandra.template.query

9.10. Querying Rows 챕터 확인

Reference

https://docs.spring.io/spring-data/cassandra/docs/current/reference/html/