如何使用 Flink Cassandra Connector 编写管理 Cassandra 服务？

Question

我可以使用以下代码片段连接到 AWS Managed Cassandra Service。

CassandraSink.addSink(cassandraEntityStream)
    .setClusterBuilder(
        new ClusterBuilder() {

            private static final long serialVersionUID = 2793938419775311824L;

            @Override
            public Cluster buildCluster(Cluster.Builder builder) {
                return builder
                    .addContactPoint("cassandra.ap-northeast-1.amazonaws.com")
                    .withPort(9142)
                    .withSSL()
                    .withCredentials(
                        "username",
                        "password")
                    .withLoadBalancingPolicy(
                        DCAwareRoundRobinPolicy
                            .builder()
                            .withLocalDc("ap-northeast-1")
                            .build())
                    //.withQueryOptions(option)
                    .build();
            }
        })
    .setMapperOptions(() -> new Mapper.Option[] {Mapper.Option.saveNullFields(true)})
    .build()
    .name("Write to Cassandra")
    .uid("cassandra_sink");

我在将 Stream POJO 写入 Cassandra 时遇到以下异常。

com.datastax.driver.core.exceptions.InvalidQueryException: Consistency level LOCAL_ONE is not supported for this operation. Supported consistency levels are: LOCAL_QUORUM

我能够在另一个项目中解决这个问题（不使用 flink），通过设置 ConsistencyLevel = LOCAL_QUORUM，使用下面的代码片段。

QueryOptions option = new QueryOptions();
option.setConsistencyLevel(ConsistencyLevel.LOCAL_QUORUM);

final Cluster cluster =
    Cluster.builder()
        .addContactPoint("cassandra.ap-northeast-1.amazonaws.com")
        .withPort(9142)
        .withSSL()
        .withQueryOptions(option) // NOTE
        .withAuthProvider(
            new PlainTextAuthProvider(
                "username",
                "password"))
        .withLoadBalancingPolicy(
            DCAwareRoundRobinPolicy.builder().withLocalDc("ap-northeast-1").build())
        .build();
final Session session = cluster.connect("test");

当我在 flink 中尝试同样的操作时，出现以下错误：

Exception in thread "main" org.apache.flink.api.common.InvalidProgramException: com.datastax.driver.core.QueryOptions@130161f7 is not serializable. The object probably contains or references non serializable fields.

有什么我遗漏的吗？请详细说明如何使用 Flink Cassandra 连接器 connect/write 到 MCS。

PS:

我使用下面的命令创建键空间。

    CREATE KEYSPACE "test"
    WITH
        REPLICATION = {'class': 'SingleRegionStrategy'}

我没有在我的代码中使用 AmazonRootCA1.pem。
我没有在我的代码或环境中使用 cassandra_truststore.jks。
我安装了证书 temp_file.der 证书，它是按照 these 步骤创建的。
我使用的是 Flink 1.8.2，因为这是 Kinesis Data Analytics 中可用的环境版本。

更新 07-04-2020

我可以通过为 QueryOptions 创建一个可序列化的包装器来解决序列化问题。请在下面找到代码片段：

import com.datastax.driver.core.QueryOptions;
import java.io.Serializable;

public class QueryOptionsSerializable extends QueryOptions implements Serializable {

  private static final long serialVersionUID = 2793938419775311824L;
}

使用此解决方案，我能够在代码中将一致性级别设置为 LOCAL_QUORUM，并且毫无例外地设置为运行。

    // Setting consistency level
    QueryOptionsSerializable option = new QueryOptionsSerializable();
    option.setConsistencyLevel(ConsistencyLevel.LOCAL_QUORUM);


    CassandraSink.addSink(entityStream)
        .setClusterBuilder(
            new ClusterBuilder() {

              private static final long serialVersionUID = 2793938419775311824L;

              @Override
              public Cluster buildCluster(Cluster.Builder builder) {
                Cluster.Builder tempBuilder = builder.addContactPoint(host).withPort(port);

                if (isSSLEnabled) {
                  // enable SSL config if isSSLEnabled flag is ON.
                  tempBuilder.withSSL();
                }

                if (username != null && password != null) {
                  // if username & password is provided, use it for connection.
                  tempBuilder.withCredentials(username, password);
                }

                tempBuilder.withQueryOptions(option);

                return tempBuilder.build();
              }
            })
        .setMapperOptions(() -> new Mapper.Option[] {Mapper.Option.saveNullFields(true)})
        .setDefaultKeyspace(keyspace)
        .build()
        .name("Write to Cassandra")
        .uid("cassandra_sink");

但是在写入 MCS 时，我遇到了同样的错误：

com.datastax.driver.core.exceptions.InvalidQueryException: Consistency level LOCAL_ONE is not supported for this operation. Supported consistency levels are: LOCAL_QUORUM

任何帮助将不胜感激！

Answer 1

终于想通了。这是关于使用 @Table 注释的设置一致性。

下面提供的代码片段：

@Table(name = "report", readConsistency = "LOCAL_QUORUM", writeConsistency = "LOCAL_QUORUM")
public class SampleEntity {

  @Column(name = "user_id")
  @PartitionKey(0)
  private String userId;


  @Column(name = "join_date")
  @PartitionKey(0)
  private String joinDate;

}

如何使用 Flink Cassandra Connector 编写管理 Cassandra 服务？

How to write to Manage Cassandra Service using Flink Cassandra Connector?

amazon-web-services

cassandra

apache-flink

flink-streaming

amazon-keyspaces