HBase，
标记下：先翻译下HBase,hadoop未必全部需要，HBase不可少（构建在Hadoop的HDFS之上，实际上依赖于Hadoop，如果只是测试在单机运行，不需要安装配置Hadoop，如果需要分布式，还是需要的），看了下cassandra，accumulo，都大同小异，主要是没有深入到源码级别。
When Would I Use HBase?
Use HBase when you need random, realtime read/write access to your Big Data. This project's goal is the hosting of very large tables -- billions of rows X millions of columns -- atop clusters of commodity hardware. HBase is an open-source, distributed, versioned, column-oriented store modeled after Google's Bigtable: A Distributed Storage System for Structured Data by Chang et al. Just as Bigtable leverages the distributed data storage provided by the Google File System, HBase provides Bigtable-like capabilities on top of Hadoop and HDFS.
何时使用HBase？
如果需要随机，实时读写Big Data数据。这项目目标是支持巨型表——几十亿行，几百万烈——构建在集群硬件之上。
HBase是开源的，分布式，版本化的，面向列方式存储的，以Google的BigTable为模型。正如Google的GFS中，Bigtable在分布式存储上的核心，HBase是Hadoop和HDFS的分布式存储核心。
Features
- Linear and modular scalability.
- Strictly consistent reads and writes.
- Automatic and configurable sharding of tables
- Automatic failover support between RegionServers.
- Convenient base classes for backing Hadoop MapReduce jobs with HBase tables.
- Easy to use Java API for client access.
- Block cache and Bloom Filters for real-time queries.
- Query predicate push down via server side Filters
- Thrift gateway and a REST-ful Web service that supports XML, Protobuf, and binary data encoding options
- Extensible jruby-based (JIRB) shell
- Support for exporting metrics via the Hadoop metrics subsystem to files or Ganglia; or via JMX
特性
JIRB的启动方式：
$ ./bin/hbase org.jruby.Main PATH_TO_SCRIPT
PATH_TO_SCRIPT，是一个.rb文件。ruby，python这种还真是挺火的...