Table of Contents
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
', ENCODE_ON_DISK => 'true', 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
', ENCODE_ON_DISK => 'true', 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
confiurations.
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>