I have accumulated some knowledge and know-how about MapReduce, Hadoop, and HBase since I participated in some projects. From hence, I’ll post the know-how of HBase by period. Today, I’m going to introduce a way to make a hbase table in java.
HBase provides two ways to allow a Hbase client to connect HBase master. One is to use a instance of HBaseAdmin class. HBaseAdmin provides some methods for creating, modifying, and deleting tables and column families. Another way is to use an instance of HTable class. This class almost provides some methods to manipulate data like inserting, modifying, and deleting rows and cells.
Thus, in order to make a hbase table, we need to connect a HBase master by initializing a instance of HBaseAdmin like line 4. HBaseAdmin requires an instance of HBaseConfiguration. If necessary, you may set some configurations like line 2.
In order to describe HBase schema, we make an instances of HColumnDescriptor for each column family. In addition to column family names, HColumnDescriptor enables you to set various parameters, such as maxVersions, compression type, timeToLive, and bloomFilter. Then, we can create a HBase table by invoking createTable like line 10.
HBaseConfiguration conf = new HBaseConfiguration(); conf.set("hbase.master","localhost:60000"); HBaseAdmin hbase = new HBaseAdmin(conf); HTableDescriptor desc = new HTableDescriptor("TEST"); HColumnDescriptor meta = new HColumnDescriptor("personal".getBytes()); HColumnDescriptor prefix = new HColumnDescriptor("account".getBytes()); desc.addFamily(meta); desc.addFamily(prefix); hbase.createTable(desc);
Finally, you can check your hbase table as the following commands.
c0d3h4ck@code:~/Development/hbase$ bin/hbase shell HBase Shell; enter 'help<RETURN>' for list of supported commands. Version: 0.20.1, r822817, Wed Oct 7 11:55:42 PDT 2009 hbase(main):001:0> list TEST 1 row(s) in 0.0940 seconds