我在我的机器上使用Cassandra 1.2.4(
Windows 7).
我的DC1中有3个节点,在我的机器上.我只使用一台DC(我的机器).我确实保留了复制因子= 2和“HConsistencyLevel.ONE”.但是,当其中一个节点关闭,并且我尝试读取或写入DB时,我收到错误 – “可能没有足够的副本来处理一致性级别.”.
我的印象是,当我们将一致性级别保持为“ONE”时,即使一个节点启动,写入/读取也应该没有错误.但是我得到了这个错误.有人可以纠正我,因为我在这里做错了.我在谷歌搜索但是没有得到很多关于此错误的帮助,尽管此错误非常相关.我希望在节点发生故障时进行读/写操作.以下是我的代码.
String keySpaceName="kspace"; String clusterName="Test Cluster"; String columFamilyName="ktable"; String host="127.0.0.1:9160,127.0.0.2:9161,127.0.0.3:9162"; int replicationFactor=2; CassandraHostConfigurator cassandraHostConfigurator = new CassandraHostConfigurator(host); Cluster cluster = HFactory.getOrCreateCluster(clusterName,cassandraHostConfigurator); KeyspaceDefinition keyspaceDef = cluster.describeKeyspace(keySpaceName); ConfigurableConsistencyLevel configurableConsistencyLevel = new ConfigurableConsistencyLevel(); Map<String,HConsistencyLevel> clmap = new HashMap<String,HConsistencyLevel>(); // Define CL.ONE for ColumnFamily "ktable" clmap.put(columFamilyName,HConsistencyLevel.ONE); configurableConsistencyLevel.setReadCfConsistencyLevels(clmap); configurableConsistencyLevel.setWriteCfConsistencyLevels(clmap); if(keyspaceDef==null) { KeyspaceDefinition newKeyspace = HFactory.createKeyspaceDefinition( keySpaceName,ThriftKsDef.DEF_STRATEGY_CLASS,replicationFactor,null); cluster.addKeyspace(newKeyspace,true); } Keyspace keyspace = HFactory.createKeyspace(keySpaceName,cluster,configurableConsistencyLevel); StringSerializer ss = StringSerializer.get(); ColumnFamilyTemplate<String,String> cft = new ThriftColumnFamilyTemplate<String,String>(keyspace,columFamilyName,ss,ss); ColumnFamilyUpdater<String,String> updater = cft.createUpdater("xkey"); UUID uid = new UUID(); updater.setValue("id",Long.toString(uid.getClockSeqAndNode()),ss); updater.setValue("name","Catherine",ss); updater.setValue("state","GA",ss); cft.update(updater);
解决方法
将复制因子更改为1,即您已设置的节点数.我确实得到了相同的错误来运用这些例子.