HBase建表中,默認指定的是一個版本(建表時默認的VERSION是1),若要保留多個版本信息,需在建立表時,就要指定版本數。spa
eg.create 'scores',{NAME=>'course',VERSIONS=>2}get
首先,先建立一張表,而後添加兩條記錄
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'
it
0 row(s) in 0.0100 secondsio
hbase(main):081:0> scan 'scores'
ROW COLUMN+CELL
Tom column=course:math, timestamp=1394097631387, value=97
date
1 row(s) in 0.0190 secondsim
hbase(main):082:0> put 'scores','Tom','course:math','100' 時間戳
0 row(s) in 0.0080 seconds
hbase(main):026:0> scan 'scores'
ROW COLUMN+CELL
Tom column=course:math, timestamp=1394097651029, value=100
ember
1 row(s) in 0.0110 seconds數據
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
從上面能夠看到,HBASE默認scan出來的結果是最後一條時間戳的記錄,那麼如何把這兩條都scan出來呢,
這時候能夠加入VERSIONS這個約束條件:
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,已經把這條記錄都scan出來了。
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
從上面的結果只scan出一條記錄。可知,TIMERANGE表示的是」>=開始時間 and <結束時間「的【左閉右開】。再看:
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,這樣就明白了。
不過上面的加了VERSIONS=>2,就能夠查到歷史的數據了,可是必須再建立表的時候加上VERSIONS,不然無效,看下面的例子:
hbase(main):082:0> create 'member','address','info'
0 row(s) in 0.4140 seconds
=> Hbase::Table - member
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
能夠看到,雖然加了VERSIONS,但get的結果是1條;這就是由於建表時默認的VERSION是1.
修改VERSIONS:
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
那麼如今就能夠把倆條記錄get出來了,以下:
hbase(main):049:0> get 'member','wanglei',{COLUMN=>'info:age',TIMERANGE=>[1394439539837,1394441161596],VERSIONS=>2}或get 'member','wanglei',{COLUMN=>'info:age',VERSIONS=>2}
COLUMN CELL
info:age timestamp=1394441161595, value=101
info:age timestamp=1394439539837, value=100
2 row(s) in 0.0080 seconds
時間