HBase change split policy on an existing table

hbase(main)::> create 'test_table_region', 'username'
 row(s) in 1.2150 seconds

hbase(main)::> put 'test_table_region', '', 'username:nick' ,''
 row(s) in 0.0050 seconds

hbase(main)::> scan 'test_table_region'
ROW                                COLUMN+CELL
                                  column=username:nick, timestamp=, value=
 row(s) in 0.1370 seconds

hbase(main)::> describe 'test_table_region'
DESCRIPTION                                                                           ENABLED
 {NAME => 'test_table_region', FAMILIES => [{NAME => 'username', DATA_BLOCK_ENCODING  true
 => 'NONE', BLOOMFILTER => 'NONE', REPLICATION_SCOPE => '', VERSIONS => '', COMPRES
 SION => 'NONE', MIN_VERSIONS => '', TTL => '', KEEP_DELETED_CELLS => 'fal
 se', BLOCKSIZE => '', IN_MEMORY => 'false', ENCODE_ON_DISK => 'true', BLOCKCACH
 E => 'true'}]}
 row(s) in 0.4040 seconds

hbase(main)::> disable 'test_table_region'
 row(s) in 3.1710 seconds

hbase(main)::> alter 'test_table_region', {METHOD => 'table_att', SPLIT_POLICY => 'org.apache.hadoop.hbase.regionserver.ConstantSizeRegionSplitPolicy', MAX_FILESIZE => ''}
Updating all regions with the new schema...
/ regions updated.
Done.
 row(s) in 4.5130 seconds

hbase(main)::> enable 'test_table_region'
 row(s) in 6.0330 seconds

hbase(main)::> describe 'test_table_region'
DESCRIPTION                                                                           ENABLED
 {NAME => 'test_table_region', SPLIT_POLICY => 'org.apache.hadoop.hbase.regionserver. true
 ConstantSizeRegionSplitPolicy', MAX_FILESIZE => '', FAMILIES => [{NAME =>
 'username', DATA_BLOCK_ENCODING => 'NONE', BLOOMFILTER => 'NONE', REPLICATION_SCOPE
 => '', COMPRESSION => 'NONE', VERSIONS => '', TTL => '', MIN_VERSIONS =>
  '', KEEP_DELETED_CELLS => 'false', BLOCKSIZE => '', ENCODE_ON_DISK => 'true',
  IN_MEMORY => 'false', BLOCKCACHE => 'true'}]}
 row(s) in 0.4610 seconds

the alter split_policy does not work for hbase before version 0.94

we need to use java code to change the split policy of an existing table

 protected void changeSplitPolicy(String tableName, Configuration conf) throws IOException, IllegalAccessException, InstantiationException {
    HBaseAdmin admin = new HBaseAdmin(conf);
    HTable hTable = new HTable(conf, tableName);
    HTableDescriptor htd = hTable.getTableDescriptor();
    HTableDescriptor tableDesc = new HTableDescriptor(htd);

    tableDesc.setValue(HTableDescriptor.SPLIT_POLICY, ConstantSizeRegionSplitPolicy.class.getName());
    tableDesc.setValue(HTableDescriptor.MAX_FILESIZE, "5000000000");

    if(admin.isTableEnabled(tableName)) {
      admin.disableTable(tableName);
    }
    admin.modifyTable(Bytes.toBytes(tableName), tableDesc);
    hTable.close();
    admin.close();
    System.out.println("change split policy over");
  }