How to find/tell region name for given hbase rowkey

[#1]

Simple API to find region name for given row key. It will also give you hint about the region - Where key will be placed.

To compile class:

$JAVA_HOME/bin/javac -cp `hbase classpath`: Regionfinder.java

To run tool:

$JAVA_HOME/bin/java -cp `hbase classpath`: Regionfinder <tablename> <rowkey>

Regionfinder.java

import java.io.IOException;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.HBaseConfiguration;
import org.apache.hadoop.hbase.HRegionLocation;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.client.Connection;
import org.apache.hadoop.hbase.client.ConnectionFactory;
import org.apache.hadoop.hbase.client.Get;
import org.apache.hadoop.hbase.client.RegionLocator;
import org.apache.hadoop.hbase.client.Result;
import org.apache.hadoop.hbase.client.Table;
import org.apache.hadoop.hbase.util.Bytes;

public class Regionfinder {
        private static void usage(String[] args) {
                if (args.length < 2) {
                        System.out.println("$JAVA_HOME/bin/java -cp `hbase classpath`: Regionfinder <tablename> <rowkey>");
                        System.exit(-1);
                }
        }

        public static void main(String[] args) throws IOException {
                usage(args);
                TableName tablename = TableName.valueOf(args[0]);
                String rowkey = args[1];
                byte[] keyInBytes = Bytes.toBytes(rowkey);
                Configuration conf = HBaseConfiguration.create();
                Connection connection = ConnectionFactory.createConnection(conf);
                Table table = connection.getTable(tablename);
                RegionLocator regionLocater = connection.getRegionLocator(tablename);
                HRegionLocation regionLocation = regionLocater.getRegionLocation(keyInBytes);
                Result result = table.get(new Get(keyInBytes));
                if(result.isEmpty()){
                        System.out.println("Rowkey "+rowkey+" is not exist in any region. It will be placed in region : "+regionLocation.getRegionInfo().getRegionNameAsString());
                }else{
                        System.out.println("Table Name = " + tablename + "\n" + "Row Key = " + rowkey + "\n" + "Region Server = "
                                        + regionLocation.getServerName() + "\n" + "Region Name = "
                                        + regionLocation.getRegionInfo().getRegionNameAsString() + "\n" + "Encoded Region Name = "
                                        + regionLocation.getRegionInfo().getEncodedName());
                }
        }
}

Ex Output:
#java -cp `hbase classpath`:  Regionfinder sp 100
Table Name = sp
Row Key = 100
Region Server = hwx2633.openstacklocal,16020,1528109888044
Region Name = sp,100,1521182497105.6e87f8a4f3bf7c2762d644dba8e98022.
Encoded Region Name = 6e87f8a4f3bf7c2762d644dba8e98022

Non existing row key:
#java -cp `hbase classpath`:  Regionfinder sp 10
Rowkey 10 is not exist in any region. It will be placed in region : sp,10,1521182497105.ecc8568cb94776ad83ee04cbb422bff0

[#2]

@Karthik Palanisamy,

This is really a good piece of information. Thanks for sharing. Keep them coming !

[#3]

@kpalanisamy 
➤ We also have a alternate hbase shell native approach through which we can determine the RegionName and RegionServer from the rowkey

$ locate_region 'namespace:tablename','rowkey'

 HOST                             REGION

Regionserver-name:16 {ENCODED => regionName, NAME => 'namespace:tablename,rowkey.regionName.', STARTKEY => 'f0046', ENDKEY => 'f0245cf'}

 1 row(s)

 Took 0.6760 seconds

 => #<Java::OrgApacheHadoopHbase::HRegionLocation:0x4070c4ff>