首先我们先了解下 hbase:meta 表，hbase是指的namespace，meta是表名，这张表存储的是整个集群的Region信息。
hbase:meta表的一个rowkey对应一个region，rowkey设计如下:
表名,region的startRowkey,region创建时的时间戳,EcodedName
例：test:vt_article,66192017090716590_4149388609714192,1542770105784.5c44f752e1012fba9eacad769185b9dd
表名 ： test:vt_article
开始rowkey ：66192017090716590_4149388609714192
创建Region时间戳：1542770105784
EncodedName ：5c44f752e1012fba9eacad769185b9dd = MD5(test:vt_article,66192017090716590_4149388609714192,1542770105784)
知道rowkey的设计方式，我们可以设计查询如下
scan 'hbase:meta',{STARTROW=>'test:vt_article,00002012072410050_3471256520905766,9999999999999',REVERSED=>true,LIMIT=>1}这里的意思是：查找表 test:vt_article ，rowkey为00002012072410050_3471256520905766，所在的region
REVERSED=>true 意思是反向查找，这里如果是正向查找，会找到 rowkey 所在Region的下一个region，原因是hbase:meta表的rowkey里面存储的是startrowkey，这种情况下我们找到rowkey所在region的下一个region。所以我们使用反向查找，可以找到我们所在的rowkey。
我们可以看下图正向查找和反向的结果区别，很明显可以看出反向查找的结果是正确的
hbase(main):007:0> scan 'hbase:meta',{STARTROW=>'test:vt_article,00002012072410050_3471256520905766,9999999999999',REVERSED=>true,LIMIT=>1}
ROW COLUMN+CELL test:vt_article,,1538280376919.87d0e49c column=info:regioninfo, timestamp=1571810629396, value={ENCODED => 87d0e49c84ed5c95440606d2d015f018, NAME => 'zh_ams_ns:vt_wei84ed5c95440606d2d015f018. bo,,1538280376919.87d0e49c84ed5c95440606d2d015f018.', STARTKEY => '', ENDKEY => '004b2016100709180_4027872588656361'} test:vt_article,,1538280376919.87d0e49c column=info:seqnumDuringOpen, timestamp=1571810629396, value=\x00\x00\x00\x00\x00t\xBA\xB4 84ed5c95440606d2d015f018. test:vt_article,,1538280376919.87d0e49c column=info:server, timestamp=1571810629396, value=hostname1:16020 84ed5c95440606d2d015f018. test:vt_article,,1538280376919.87d0e49c column=info:serverstartcode, timestamp=1571810629396, value=1571810311419 84ed5c95440606d2d015f018. test:vt_article,,1538280376919.87d0e49c column=info:sn, timestamp=1571810628942, value=hostname1,16020,1571810311419 84ed5c95440606d2d015f018. test:vt_article,,1538280376919.87d0e49c column=info:state, timestamp=1571810629396, value=OPEN 84ed5c95440606d2d015f018.
1 row(s)
Took 0.0204 seconds
hbase(main):008:0> scan 'hbase:meta',{STARTROW=>'test:vt_article,00002012072410050_3471256520905766,9999999999999',LIMIT=>1}
ROW COLUMN+CELL test:vt_article,004b2016100709180_40278 column=info:regioninfo, timestamp=1571808696621, value={ENCODED => cc232ffa5439b5b8d7b2a34be789802e, NAME => 'zh_ams_ns:vt_wei72588656361,1571222677329.cc232ffa5439b5b8 bo,004b2016100709180_4027872588656361,1571222677329.cc232ffa5439b5b8d7b2a34be789802e.', STARTKEY => '004b2016100709180_4027872d7b2a34be789802e. 588656361', ENDKEY => '00712017050420290_4103780394008107'} test:vt_article,004b2016100709180_40278 column=info:seqnumDuringOpen, timestamp=1571808696621, value=\x00\x00\x00\x00\x00u\xA8\x8C 72588656361,1571222677329.cc232ffa5439b5b8 d7b2a34be789802e. test:vt_article,004b2016100709180_40278 column=info:server, timestamp=1571808696621, value=hostname2:16020 72588656361,1571222677329.cc232ffa5439b5b8 d7b2a34be789802e. test:vt_article,004b2016100709180_40278 column=info:serverstartcode, timestamp=1571808696621, value=1571808447292 72588656361,1571222677329.cc232ffa5439b5b8 d7b2a34be789802e. test:vt_article,004b2016100709180_40278 column=info:sn, timestamp=1571808609135, value=hostname2,16020,1571808447292 72588656361,1571222677329.cc232ffa5439b5b8 d7b2a34be789802e. test:vt_article,004b2016100709180_40278 column=info:state, timestamp=1571808696621, value=OPEN 72588656361,1571222677329.cc232ffa5439b5b8 d7b2a34be789802e.
1 row(s)
Took 0.0190 seconds
)
