java Hector 和 Cassandra 的基础知识
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Basics of Hector & Cassandra
提问by Henry
I'm working with Cassandra-0.8.2. I am working with the most recent version of Hector & My java version is 1.6.0_26
我正在使用 Cassandra-0.8.2。我正在使用最新版本的 Hector & 我的 java 版本是 1.6.0_26
I'm very new to Cassandra & Hector.
我对 Cassandra & Hector 很陌生。
What I'm trying to do: 1. connect to an up & running instance of cassandra on a different server. I know it's running b/c I can ssh through my terminal into the server running this Cassandra instance and run the CLI with full functionality. 2. then I want to connect to a keyspace & create a column family and then add a value to that column family through Hector.
我想要做的是： 1. 连接到不同服务器上的 cassandra 启动和运行实例。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并创建一个列族，然后通过 Hector 向该列族添加一个值。
I think my problem is that this running instance of Cassandra on this server might not be configured to get commands that are not local. I think my next step will be to add a local instance of Cassandra on the cpu I'm working on and try to do this locally. What do you think?
我认为我的问题是此服务器上的 Cassandra 运行实例可能未配置为获取非本地命令。我认为我的下一步将是在我正在处理的 cpu 上添加 Cassandra 的本地实例，并尝试在本地执行此操作。你怎么认为？
Here's my Java code:
这是我的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"));
}
}
My ERROR is:
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.doInKeyspace(MutatorImpl.java:222)
at me.prettyprint.cassandra.model.MutatorImpl.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
Thank you in advance for your help.
预先感谢您的帮助。
采纳答案by sbridges
The exception you are getting is,
你得到的例外是，
why:Keyspace apples does not exist
In your code, this line does not actually create the keyspace,
在您的代码中，这一行实际上并未创建键空间，
Keyspace keyspace = HFactory.createKeyspace("apples", cluster);
As described here, this is the code you need to define your keyspace,
如上所述这里，这就是你需要定义你的密钥空间的代码，
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);
回答by zznate
We also have a getting started guideup on the wiki as well which might be of some help.
我们在 wiki 上还有一个入门指南，这可能会有所帮助。
