HBase之表空间

1、介绍
在HBase中，namespace命名空间指对一组表的逻辑分组，类似RDBMS中的database，方便对表在业务上划分。Apache HBase从0.98.0, 0.95.2两个版本开始支持namespace级别的授权操作，HBase全局管理员可以创建、修改和回收namespace的授权。
 
2、namespace
HBase系统默认定义了两个缺省的namespace
hbase：系统内建表，包括namespace和meta表
default：用户建表时未指定namespace的表都创建在此
 
创建namespace:
hbase(main):010:0* create_namespace 'datamanage'
 
 
查看namespace:
hbase(main):011:0> describe_namespace 'datamanage'
  DESCRIPTION              
   {NAME =>'datamanage'}                                                                                                                
列出所有namespace:
hbase(main):012:0> list_namespace
    NAMESPACE
     datamanage                                                                                                                       
     default  
     hbase   
 
在namespace下创建表:       
hbase(main):013:0> create 'datamanage:testtable','colfam01'
    => Hbase::Table - datamanage:testtable
查看namespace下的表
hbase(main):015:0> list_namespace_tables 'datamanage'
    TABLE                
    testtable   
 
删除namespace:
 
hbase(main):016:0> drop_namespace 'datamanage'
 
ERROR: org.apache.hadoop.hbase.constraint.ConstraintException: Only empty namespaces can be removed. Namespace datamanage has 1 tables
        at org.apache.hadoop.hbase.master.TableNamespaceManager.remove(TableNamespaceManager.java:200)
        at org.apache.hadoop.hbase.master.HMaster.deleteNamespace(HMaster.java:2488)
        at org.apache.hadoop.hbase.master.MasterRpcServices.deleteNamespace(MasterRpcServices.java:489)
        at org.apache.hadoop.hbase.protobuf.generated.MasterProtos$MasterService$2.callBlockingMethod(MasterProtos.java:55730)
        at org.apache.hadoop.hbase.ipc.RpcServer.call(RpcServer.java:2178)
        at org.apache.hadoop.hbase.ipc.CallRunner.run(CallRunner.java:112)
        at org.apache.hadoop.hbase.ipc.RpcExecutor.consumerLoop(RpcExecutor.java:133)
        at org.apache.hadoop.hbase.ipc.RpcExecutor$1.run(RpcExecutor.java:108)
        at java.lang.Thread.run(Thread.java:745)
 
Here is some help for this command:
Drop the named namespace. The namespace must be empty.
#删除表
hbase(main):017:0> disable 'datamanage:testtable'
hbase(main):018:0> drop 'datamanage:testtable'
#删除datamanage命名空间
hbase(main):019:0> drop_namespace 'datamanage'