目錄
spring data 操作 Cassandra
添加依賴和配置
- 添加依賴
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-cassandra</artifactId>
</dependency>
- 添加配置
spring.data.cassandra.keyspace-name=myKeySpace
spring.data.cassandra.contact-points=myContactPoints
spring.data.cassandra.port=9042
spring.data.cassandra.schema-action=NONE
定義key, data 和 建表
此處以counter表為例, 表示用戶在某一個類別下的點擊量。
@PrimaryKeyClass
public class UserCategoryKey implements Serializable {
@PrimaryKeyColumn(name = "user_id", ordinal = 0, type = PrimaryKeyType.PARTITIONED)
private String userId;
@PrimaryKeyColumn(name = "category_id", ordinal = 1, type = PrimaryKeyType.CLUSTERED)
private Integer categoryId;
}
@Table("user_category")
public class UserCategory {
@PrimaryKey
private UserCategoryKey key;
@Column("click_cnt")
private Long clickCnt;
}
創建表的schema：
-- Cannot set default_time_to_live on a table with counters
CREATE TABLE user_category
(
user_id text,
category_id int,
click_cnt counter
PRIMARY KEY ((user_id), category_id)
);
限制:
- 非counter字段必須包含在主鍵中。
使用repository操作數據
@Repository
public interface UserCategoryRepository extends CassandraRepository<UserCategory, UserCategoryKey> {
@Modifying
@Transactional
@Query(value = "update user_category set click_cnt = click_cnt + :cnt where " +
"user_id = :#{#key.userId} and category_id = :#{#key.categoryId}")
public void incClickCnt(@Param("key") UserCategoryKey key, @Param("cnt") Long cnt);
}
使用CassandraOperations 操作數據
CassandraOperations 可以直接注入：
@Autowired
protected CassandraOperations cassandraTemplate;
/**
* update user_category set click_cnt = click_cnt + 1 where user_id='user1' and category_id = 2001
*/
public Boolean incClickCounter(UserCategoryKey key, Long cnt) {
try {
//update table
Update update = QueryBuilder.update("user_category");
//set
update.with(QueryBuilder.incr("click_cnt", cnt));
//where conditions
update.where(QueryBuilder.eq("user_id", key.getUserId()))
.and(QueryBuilder.eq("category_id", key.getCategoryId()));
cassandraTemplate.getCqlOperations().execute(update);
return true;
} catch (Exception e) {
LOG.error("incClickCounter exception, msg:{}", e.getMessage(), e);
}
return false;
}
踩坑二三事
1. 只能對counter字段進行加減操作
如果對非counter字段進行加減操作，報錯如下：
Query; CQL [update user_category set click_cnt = click_cnt + ? where user_id = ? and category_id = ?]; Invalid operation (click_cnt = click_cnt + ?) for non counter column click_cnt; nested exception is com.datastax.driver.core.exceptions.InvalidQueryException: Invalid operation (click_cnt = click_cnt + ?) for non counter column click_cnt
2. 參數位置要求
對於 click_cnt = click_cnt + :cnt 如果參數放在前面，即click_cnt = :cnt + click_cnt. 如下語句 update user_category set click_cnt = :cnt + click_cnt where user_id = 'user1' and category_id = 1, 則報錯：
Query; CQL [update user_category set click_cnt = ? + click_cnt where user_id = ? and category_id = ?]; Invalid operation (click_cnt = ? - click_cnt) for non list column click_cnt; nested exception is com.datastax.driver.core.exceptions.InvalidQueryException: Invalid operation (click_cnt = ? - click_cnt) for non list column click_cnt
4. counter操作的參數需為long型
如下，將方法中參數cnt定義為Integer：
@Query(value = "update user_category set click_cnt = click_cnt + :cnt where user_id = 'user1' and category_id = 1")
public void incClickCnt(@Param("cnt") Integer cnt);
報錯如下：
Query; CQL [update user_category set click_cnt = click_cnt + ? where user_id=? and category_id = ?]; Expected 8 or 0 byte long (4); nested exception is com.datastax.driver.core.exceptions.InvalidQueryException: Expected 8 or 0 byte long (4)
5. in語句不要加小括號
如下：
@Query(value = "update user_category set click_cnt = click_cnt + 1 where user_id='user1' and category_id in :categoryIdList")
public void bathUpdate(@Param("categoryIdList") List<Integer> categoryIdList);
若改為news_id in (:newsIdList), 則會報錯：
org.springframework.data.cassandra.CassandraInvalidQueryException: Query; CQL [update user_category set click_cnt=click_cnt+1 where user_id=? and category_id in (?)]; Expected 4 or 0 byte int (28); nested exception is com.datastax.driver.core.exceptions.InvalidQueryException: Expected 4 or 0 byte int (28 ）
6. 關於CassandraOperations
如果在unit test 中直接注入CassandraOperations測試，會報JmxReporter相關的錯。但是如果在業務代碼中直接注入，不會有問題。如果需要在單測中使用CassandraOperations，可以手動build一個Cluster，並禁用 JmxReporter 和 metrics。
參考：
Cassandra 計數器counter類型和它的限制
Cassandra數據建模
最后：
沒有很多時間逐個搞清楚每個問題的深層次原因啦，記錄下踩的坑，以鑒他人~