HBASE中TIMERANGE和VERSION的使用

                                                    HBASE中TIMERANGE和VERSION的使用

首先，先创建一张表，然后添加两条记录

hbase(main):079:0> create 'scores',{NAME=>'course',VERSIONS=>2}
0 row(s) in 0.9590 seconds
 hbase(main):080:0> put 'scores','Tom','course:math','97'
0 row(s) in 0.0100 seconds

hbase(main):081:0> scan 'scores'
ROW                                        COLUMN+CELL
Tom                                       column=course:math, timestamp=1394097631387, value=97
1 row(s) in 0.0190 seconds

hbase(main):082:0> put 'scores','Tom','course:math','100'
0 row(s) in 0.0080 seconds

hbase(main):026:0> scan 'scores'
ROW                                        COLUMN+CELL
Tom                                       column=course:math, timestamp=1394097651029, value=100
1 row(s) in 0.0110 seconds

hbase(main):027:0> scan 'scores',{TIMERANGE=>[1394097631387,1394097651029]}
ROW                                        COLUMN+CELL
Tom                                       column=course:math, timestamp=1394097631387, value=97
1 row(s) in 0.0210 seconds

hbase(main):028:0> scan 'scores',{TIMERANGE=>[1394097631387,1394097651030]}
ROW                                        COLUMN+CELL
Tom                                       column=course:math, timestamp=1394097651029, value=100
1 row(s) in 0.0100 seconds

从上面可以看到，HBASE默认scan出来的结果是最后一条时间戳的记录，那么如何把这两条都scan出来呢，
这时候可以加入VERSIONS这个约束条件：

点击(此处)折叠或打开

hbase(main):032:0> scan 'scores',{VERSIONS=>2}
ROW                                        COLUMN+CELL
Tom                                       column=course:math, timestamp=1394097651029, value=100
Tom                                       column=course:math, timestamp=1394097631387, value=97
1 row(s) in 0.0130 seconds

 上面的命令，已经把这条记录都scan出来了。

再看下面的例子：

scan 'scores',{TIMERANGE=>[1394097631386,1394097651029],VERSIONS=>2}
ROW                                        COLUMN+CELL
 Tom                                       column=course:math, timestamp=1394097631387, value=97
1 row(s) in 0.0130 seconds

 从上面的结果只scan出一条记录。可知，TIMERANGE表示的是”>=开始时间 and <结束时间“的。再看：
点击(此处)折叠或打开

hbase(main):003:0> scan 'scores',{TIMERANGE=>[1394097631386,1394097651030],VERSIONS=>2}
ROW                                        COLUMN+CELL
 Tom                                       column=course:math, timestamp=1394097651029, value=100
 Tom                                       column=course:math, timestamp=1394097631387, value=97
1 row(s) in 0.0100 seconds

 OK，这样就明白了。
 不过上面的加了VERSIONS=>2，就可以查到历史的数据了，但是必须再创建表的时候加上VERSIONS,否则无效,看下面的例子：

hbase(main):082:0> create 'member','address','info'
0 row(s) in 0.4140 seconds

=> Hbase::Table - member

点击(此处)折叠或打开

hbase(main):093:0> put 'member','wanglei','info:age','24'
0 row(s) in 0.0730 seconds

hbase(main):093:1>get 'member','wanglei',{COLUMN=>'info:age'}
COLUMN         CELL
 info:age                          timestamp=1394438746187, value=24
hbase(main):093:7> put 'member','wanglei','info:age','99'
0 row(s) in 0.0730 seconds
hbase(main):093:18> get 'member','wanglei',{COLUMN=>'info:age'}
COLUMN                             CELL
info:age                          timestamp=1394439539837, value=100

       

hbase(main):022:0> get 'member','wanglei',{COLUMN=>'info:age',TIMERANGE=>[1394438746187,1394439539838],VERSIONS=>2}
COLUMN                             CELL
 info:age                          imestamp=1394439539837, value=100
1 row(s) in 0.0050 seconds

 可以看到，虽然加了VERSIONS，但get的结果是1条；这就是因为建表时默认的VERSION是1.
修改VERSIONS：
点击(此处)折叠或打开

hbase(main):029:0> alter 'member',{NAME=>'info','VERSIONS'=>2}
Updating all regions with the new schema...
0/1 regions updated.
1/1 regions updated.
Done.
0 row(s) in 2.1680 seconds

hbase(main):046:0> put 'member','wanglei','info:age','101'
0 row(s) in 0.0590 seconds

hbase(main):047:0> get 'member','wanglei',{COLUMN=>'info:age'}
COLUMN                             CELL
 info:age                          timestamp=1394441161595, value=101
1 row(s) in 0.0120 seconds

   那么现在就可以把倆条记录get出来了,如下：
  

hbase(main):049:0> get 'member','wanglei',{COLUMN=>'info:age',TIMERANGE=>[1394439539837,1394441161596],VERSIONS=>2}
COLUMN                             CELL
 info:age                          timestamp=1394441161595, value=101
 info:age                          timestamp=1394439539837, value=100
2 row(s) in 0.0080 seconds