The Apache HBase Shell is (J)Ruby's IRB with some HBase particular commands added. Anything you can do in IRB, you should be able to do in the HBase Shell. To run the HBase shell, do as follows: $ ./bin/hbase shell Type help and then <RETURN> to see a listing of shell commands and options. Browse at least the paragraphs at the end of the help emission for the gist of how variables and command arguments are entered into the HBase shell; in particular note how table names, rows, and columns, etc., must be quoted. See for example basic shell operation. Here is a nicely formatted listing of all shell commands by Rajeshbabu Chintaguntla.

For examples scripting Apache HBase, look in the HBase bin directory. Look at the files that end in *.rb. To run one of these files, do as follows: $ ./bin/hbase org.jruby.Main PATH_TO_SCRIPT

HBase 0.95 adds shell commands that provide a jruby-style object-oriented references for tables. Previously all of the shell commands that act upon a table have a procedural style that always took the name of the table as an argument. HBase 0.95 introduces the ability to assign a table to a jruby variable. The table reference can be used to perform data read write operations such as puts, scans, and gets well as admin functionality such as disabling, dropping, describing tables. For example, previously you would always specify a table name: hbase(main):000:0> create ‘t’, ‘f’ 0 row(s) in 1.0970 seconds hbase(main):001:0> put 't', 'rold', 'f', 'v' 0 row(s) in 0.0080 seconds hbase(main):002:0> scan 't' ROW COLUMN+CELL rold column=f:, timestamp=1378473207660, value=v 1 row(s) in 0.0130 seconds hbase(main):003:0> describe 't' DESCRIPTION ENABLED 't', {NAME => 'f', DATA_BLOCK_ENCODING => 'NONE', BLOOMFILTER => 'ROW', REPLICATION_ true SCOPE => '0', VERSIONS => '1', COMPRESSION => 'NONE', MIN_VERSIONS => '0', TTL => '2 147483647', KEEP_DELETED_CELLS => 'false', BLOCKSIZE => '65536', IN_MEMORY => 'false ', BLOCKCACHE => 'true'} 1 row(s) in 1.4430 seconds hbase(main):004:0> disable 't' 0 row(s) in 14.8700 seconds hbase(main):005:0> drop 't' 0 row(s) in 23.1670 seconds hbase(main):006:0> Now you can assign the table to a variable and use the results in jruby shell code. hbase(main):007 > t = create 't', 'f' 0 row(s) in 1.0970 seconds => Hbase::Table - t hbase(main):008 > t.put 'r', 'f', 'v' 0 row(s) in 0.0640 seconds hbase(main):009 > t.scan ROW COLUMN+CELL r column=f:, timestamp=1331865816290, value=v 1 row(s) in 0.0110 seconds hbase(main):010:0> t.describe DESCRIPTION ENABLED 't', {NAME => 'f', DATA_BLOCK_ENCODING => 'NONE', BLOOMFILTER => 'ROW', REPLICATION_ true SCOPE => '0', VERSIONS => '1', COMPRESSION => 'NONE', MIN_VERSIONS => '0', TTL => '2 147483647', KEEP_DELETED_CELLS => 'false', BLOCKSIZE => '65536', IN_MEMORY => 'false ', BLOCKCACHE => 'true'} 1 row(s) in 0.0210 seconds hbase(main):038:0> t.disable 0 row(s) in 6.2350 seconds hbase(main):039:0> t.drop 0 row(s) in 0.2340 seconds If the table has already been created, you can assign a Table to a variable by using the get_table method: hbase(main):011 > create 't','f' 0 row(s) in 1.2500 seconds => Hbase::Table - t hbase(main):012:0> tab = get_table 't' 0 row(s) in 0.0010 seconds => Hbase::Table - t hbase(main):013:0> tab.put ‘r1’ ,’f’, ‘v’ 0 row(s) in 0.0100 seconds hbase(main):014:0> tab.scan ROW COLUMN+CELL r1 column=f:, timestamp=1378473876949, value=v 1 row(s) in 0.0240 seconds hbase(main):015:0> The list functionality has also been extended so that it returns a list of table names as strings. You can then use jruby to script table operations based on these names. The list_snapshots command also acts similarly. hbase(main):016 > tables = list(‘t.*’) TABLE t 1 row(s) in 0.1040 seconds => #<#<Class:0x7677ce29>:0x21d377a4> hbase(main):017:0> tables.map { |t| disable t ; drop t} 0 row(s) in 2.2510 seconds => [nil] hbase(main):018:0>

Create an .irbrc file for yourself in your home directory. Add customizations. A useful one is command history so commands are save across Shell invocations: $ more .irbrc require 'irb/ext/save-history' IRB.conf[:SAVE_HISTORY] = 100 IRB.conf[:HISTORY_FILE] = "#{ENV['HOME']}/.irb-save-history" See the ruby documentation of .irbrc to learn about other possible configurations.

To convert the date '08/08/16 20:56:29' from an hbase log into a timestamp, do: hbase(main):021:0> import java.text.SimpleDateFormat hbase(main):022:0> import java.text.ParsePosition hbase(main):023:0> SimpleDateFormat.new("yy/MM/dd HH:mm:ss").parse("08/08/16 20:56:29", ParsePosition.new(0)).getTime() => 1218920189000 To go the other direction: hbase(main):021:0> import java.util.Date hbase(main):022:0> Date.new(1218920189000).toString() => "Sat Aug 16 20:56:29 UTC 2008" To output in a format that is exactly like that of the HBase log format will take a little messing with SimpleDateFormat.

You can set a debug switch in the shell to see more output -- e.g. more of the stack trace on exception -- when you run a command: hbase> debug <RETURN>

To enable DEBUG level logging in the shell, launch it with the -d option. $ ./bin/hbase shell -d

Count command returns the number of rows in a table. It's quite fast when configured with the right CACHE hbase> count '<tablename>', CACHE => 1000 The above count fetches 1000 rows at a time. Set CACHE lower if your rows are big. Default is to fetch one row at a time.