Hector & Cassandra基础

Question

我正在使用Cassandra-0.8.2。我使用的是Hector的最新版本&我的java版本是1.6.0_26。

我对Cassandra & Hector很陌生。

我要做的是: 1.连接到另一台服务器上启动并运行的cassandra实例。我知道它正在运行b/c，我可以通过我的终端ssh进入运行这个Cassandra实例的服务器，并运行具有完整功能的CLI。2.然后我想连接到一个键空间&创建一个列族，然后通过Hector向该列族添加值。

我认为我的问题是这个服务器上运行的Cassandra实例可能没有配置为获取非本地的命令。我认为我的下一步将是在我正在处理的cpu上添加一个Cassandra的本地实例，并尝试在本地完成此操作。你认为如何？

下面是我的Java代码：

import me.prettyprint.cassandra.serializers.StringSerializer;
import me.prettyprint.cassandra.service.CassandraHostConfigurator;
import me.prettyprint.hector.api.Cluster;
import me.prettyprint.hector.api.Keyspace;
import me.prettyprint.hector.api.ddl.ColumnFamilyDefinition;
import me.prettyprint.hector.api.ddl.ComparatorType;
import me.prettyprint.hector.api.factory.HFactory;
import me.prettyprint.hector.api.mutation.Mutator;

    public class MySample {


        public static void main(String[] args) {


            Cluster cluster = HFactory.getOrCreateCluster("Test Cluster", "xxx.xxx.x.41:9160");
            Keyspace keyspace =  HFactory.createKeyspace("apples", cluster);
            ColumnFamilyDefinition cf = HFactory.createColumnFamilyDefinition("apples","ColumnFamily2",ComparatorType.UTF8TYPE);
            StringSerializer stringSerializer = StringSerializer.get();
            Mutator<String> mutator = HFactory.createMutator(keyspace, stringSerializer);
            mutator.insert("jsmith", "Standard1", HFactory.createStringColumn("first", "John"));
}
}

我的错误是：

16:22:19,852  INFO CassandraHostRetryService:37 - Downed Host Retry service started with queue size -1 and retry delay 10s
16:22:20,136  INFO JmxMonitor:54 - Registering JMX me.prettyprint.cassandra.service_Test Cluster:ServiceType=hector,MonitorType=hector
Exception in thread "main" me.prettyprint.hector.api.exceptions.HInvalidRequestException: InvalidRequestException(why:Keyspace apples does not exist)
    at me.prettyprint.cassandra.connection.HThriftClient.getCassandra(HThriftClient.java:70)
    at me.prettyprint.cassandra.connection.HConnectionManager.operateWithFailover(HConnectionManager.java:226)
    at me.prettyprint.cassandra.service.KeyspaceServiceImpl.operateWithFailover(KeyspaceServiceImpl.java:131)
    at me.prettyprint.cassandra.service.KeyspaceServiceImpl.batchMutate(KeyspaceServiceImpl.java:102)
    at me.prettyprint.cassandra.service.KeyspaceServiceImpl.batchMutate(KeyspaceServiceImpl.java:108)
    at me.prettyprint.cassandra.model.MutatorImpl$3.doInKeyspace(MutatorImpl.java:222)
    at me.prettyprint.cassandra.model.MutatorImpl$3.doInKeyspace(MutatorImpl.java:219)
    at me.prettyprint.cassandra.model.KeyspaceOperationCallback.doInKeyspaceAndMeasure(KeyspaceOperationCallback.java:20)
    at me.prettyprint.cassandra.model.ExecutingKeyspace.doExecute(ExecutingKeyspace.java:85)
    at me.prettyprint.cassandra.model.MutatorImpl.execute(MutatorImpl.java:219)
    at me.prettyprint.cassandra.model.MutatorImpl.insert(MutatorImpl.java:59)
    at org.cassandra.examples.MySample.main(MySample.java:25)
Caused by: InvalidRequestException(why:Keyspace apples does not exist)
    at org.apache.cassandra.thrift.Cassandra$set_keyspace_result.read(Cassandra.java:5302)
    at org.apache.cassandra.thrift.Cassandra$Client.recv_set_keyspace(Cassandra.java:481)
    at org.apache.cassandra.thrift.Cassandra$Client.set_keyspace(Cassandra.java:456)
    at me.prettyprint.cassandra.connection.HThriftClient.getCassandra(HThriftClient.java:68)
    ... 11 more

提前感谢您的帮助。

Answer 1

你得到的例外是，

why:Keyspace apples does not exist

在您的代码中，这一行实际上并不创建keyspace，

Keyspace keyspace =  HFactory.createKeyspace("apples", cluster);

正如here所描述的，这是定义键空间所需的代码，

ColumnFamilyDefinition cfDef = HFactory.createColumnFamilyDefinition("MyKeyspace", "ColumnFamilyName", ComparatorType.BYTESTYPE);

KeyspaceDefinition newKeyspace = HFactory.createKeyspaceDefinition("MyKeyspace", ThriftKsDef.DEF_STRATEGY_CLASS,  replicationFactor, Arrays.asList(cfDef));

// Add the schema to the cluster.
// "true" as the second param means that Hector will block until all nodes see the change.
cluster.addKeyspace(newKeyspace, true);

Answer 2

我们在维基上也有a getting started guide，这可能会有一些帮助。