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From Apache Wiki <wikidi...@apache.org>
Subject [Hadoop Wiki] Update of "Hbase/Shell" by Misty
Date Mon, 19 Oct 2015 01:20:11 GMT
Dear Wiki user,

You have subscribed to a wiki page or wiki category on "Hadoop Wiki" for change notification.

The "Hbase/Shell" page has been changed by Misty:
https://wiki.apache.org/hadoop/Hbase/Shell?action=diff&rev1=13&rev2=14

- This page describes the JRuby IRB-based HBase Shell.  It replaces the SQL-like [[Hbase/HbaseShell|HQL]],
the Shell found in HBase versions 0.1.x and previous.  Some discussion of new shell requirements
can be found in the [[Hbase/Shell/Replacement|Shell Replacement]] document.
+ The HBase Wiki is in the process of being decommissioned. The info that used to be on this
page has moved to http://hbase.apache.org/book.html#shell. Please update your bookmarks.
  
- To run the shell, do
- 
- {{{
- $ ${HBASE_HOME}/bin/hbase shell
- }}}
- You'll be presented with a prompt like the following:
- 
- {{{
- HBase Shell; enter 'help<RETURN>' for list of supported commands.
- Version: 0.2.0-dev, r670701, Mon Jun 23 17:26:36 PDT 2008
- hbase(main):001:0>
- }}}
- Type 'help' followed by a return to get a listing of commands.
- 
- == Commands ==
- {{{
- hbase(main):001:0> help
- HBASE SHELL COMMANDS:
-  alter     Alter column family schema;  pass table name and a dictionary
-            specifying new column family schema. Dictionaries are described
-            below in the GENERAL NOTES section.  Dictionary must include name
-            of column family to alter.  For example,
- 
-            To change or add the 'f1' column family in table 't1' from defaults
-            to instead keep a maximum of 5 cell VERSIONS, do:
-            hbase> alter 't1', {NAME => 'f1', VERSIONS => 5}
- 
-            To delete the 'f1' column family in table 't1', do:
-            hbase> alter 't1', {NAME => 'f1', METHOD => 'delete'}
- 
-            You can also change table-scope attributes like MAX_FILESIZE
-            MEMSTORE_FLUSHSIZE and READONLY.
- 
-            For example, to change the max size of a family to 128MB, do:
-            hbase> alter 't1', {METHOD => 'table_att', MAX_FILESIZE => '134217728'}
- 
-  count     Count the number of rows in a table. This operation may take a LONG
-            time (Run '$HADOOP_HOME/bin/hadoop jar hbase.jar rowcount' to run a
-            counting mapreduce job). Current count is shown every 1000 rows by
-            default. Count interval may be optionally specified. Examples:
- 
-            hbase> count 't1'
-            hbase> count 't1', 100000
- 
-  create    Create table; pass table name, a dictionary of specifications per
-            column family, and optionally a dictionary of table configuration.
-            Dictionaries are described below in the GENERAL NOTES section.
-            Examples:
- 
-            hbase> create 't1', {NAME => 'f1', VERSIONS => 5}
-            hbase> create 't1', {NAME => 'f1'}, {NAME => 'f2'}, {NAME => 'f3'}
-            hbase> # The above in shorthand would be the following:
-            hbase> create 't1', 'f1', 'f2', 'f3'
-            hbase> create 't1', {NAME => 'f1', VERSIONS => 1, TTL => 2592000,
\
-              BLOCKCACHE => true}
- 
-  describe  Describe the named table: e.g. "hbase> describe 't1'"
- 
-  delete    Put a delete cell value at specified table/row/column and optionally
-            timestamp coordinates.  Deletes must match the deleted cell's
-            coordinates exactly.  When scanning, a delete cell suppresses older
-            versions. Takes arguments like the 'put' command described below
- 
-  deleteall Delete all cells in a given row; pass a table name, row, and optionally
-            a column and timestamp
- 
-  disable   Disable the named table: e.g. "hbase> disable 't1'"
- 
-  drop      Drop the named table. Table must first be disabled. If table has
-            more than one region, run a major compaction on .META.:
- 
-            hbase> major_compact ".META."
- 
-  enable    Enable the named table
- 
-  exists    Does the named table exist? e.g. "hbase> exists 't1'"
- 
-  exit      Type "hbase> exit" to leave the HBase Shell
- 
-  get       Get row or cell contents; pass table name, row, and optionally
-            a dictionary of column(s), timestamp and versions.  Examples:
- 
-            hbase> get 't1', 'r1'
-            hbase> get 't1', 'r1', {COLUMN => 'c1'}
-            hbase> get 't1', 'r1', {COLUMN => ['c1', 'c2', 'c3']}
-            hbase> get 't1', 'r1', {COLUMN => 'c1', TIMESTAMP => ts1}
-            hbase> get 't1', 'r1', {COLUMN => 'c1', TIMESTAMP => ts1, \
-              VERSIONS => 4}
- 
-  list      List all tables in hbase
- 
-  put       Put a cell 'value' at specified table/row/column and optionally
-            timestamp coordinates.  To put a cell value into table 't1' at
-            row 'r1' under column 'c1' marked with the time 'ts1', do:
- 
-            hbase> put 't1', 'r1', 'c1', 'value', ts1
- 
-  tools     Listing of hbase surgery tools
- 
-  scan      Scan a table; pass table name and optionally a dictionary of scanner
-            specifications.  Scanner specifications may include one or more of
-            the following: LIMIT, STARTROW, STOPROW, TIMESTAMP, or COLUMNS.  If
-            no columns are specified, all columns will be scanned.  To scan all
-            members of a column family, leave the qualifier empty as in
-            'col_family:'.  Examples:
- 
-            hbase> scan '.META.'
-            hbase> scan '.META.', {COLUMNS => 'info:regioninfo'}
-            hbase> scan 't1', {COLUMNS => ['c1', 'c2'], LIMIT => 10, \
-              STARTROW => 'xyz'}
- 
-            For experts, there is an additional option -- CACHE_BLOCKS -- which
-            switches block caching for the scanner on (true) or off (false).  By
-            default it is enabled.  Examples:
- 
-            hbase> scan 't1', {COLUMNS => ['c1', 'c2'], CACHE_BLOCKS => false}
- 
-  status    Show cluster status. Can be 'summary', 'simple', or 'detailed'. The
-            default is 'summary'. Examples:
- 
-            hbase> status
-            hbase> status 'simple'
-            hbase> status 'summary'
-            hbase> status 'detailed'
- 
-  shutdown  Shut down the cluster.
- 
-  truncate  Disables, drops and recreates the specified table.
- 
-  version   Output this HBase version
- 
- GENERAL NOTES:
- Quote all names in the hbase shell such as table and column names.  Don't
- forget commas delimit command parameters.  Type <RETURN> after entering a
- command to run it.  Dictionaries of configuration used in the creation and
- alteration of tables are ruby Hashes. They look like this:
- 
-   {'key1' => 'value1', 'key2' => 'value2', ...}
- 
- They are opened and closed with curley-braces.  Key/values are delimited by
- the '=>' character combination.  Usually keys are predefined constants such as
- NAME, VERSIONS, COMPRESSION, etc.  Constants do not need to be quoted.  Type
- 'Object.constants' to see a (messy) list of all constants in the environment.
- 
- In case you are using binary keys or values and need to enter them into the
- shell then use double-quotes to make use of hexadecimal or octal notations,
- for example:
- 
-   hbase> get 't1', "key\x03\x3f\xcd"
-   hbase> get 't1', "key\003\023\011"
-   hbase> put 't1', "test\xef\xff", 'f1:', "\x01\x33\x40"
- 
- Using the double-quote notation you can directly use the values output by the
- shell for example during a "scan" call.
- 
- This HBase shell is the JRuby IRB with the above HBase-specific commands added.
- For more on the HBase Shell, see http://wiki.apache.org/hadoop/Hbase/Shell
- }}}
- === General Notes ===
- GENERAL NOTES: Quote all names in the hbase shell such as table and column names.  Don't
forget commas delimit command parameters.  Type <RETURN> after entering a command to
run it.  Dictionaries of configuration used in the creation and alteration of tables are ruby
Hashes. They look like this:
- 
-  . {'key1' => 'value1', 'key2' => 'value2', ...}
- 
- They are opened and closed with curley-braces.  Key/values are delimited by the '=>'
character combination.  Usually keys are predefined constants such as NAME, VERSIONS, COMPRESSION,
etc.  Constants do not need to be quoted.  Type 'Object.constants' to see a (messy) list of
all constants in the environment.
- 
- This HBase shell is the JRuby IRB with the above HBase-specific commands added.
- 
- == Anatomy Lesson ==
- The HBase Shell is a ruby script, ''${HBASE_HOME}/bin/hirb.rb'', that is passed to the JRuby
class ''org.jruby.Main'' (See ''${HBASE_HOME}/bin/shell'' and search for org.jruby.Main to
see how its done).
- 
- The ''hirb.rb' script defines a set of hbase methods (get, set, scan, etc.), sets some environment
variables, imports a few hbase-particular modules -- a results Formatter and a ruby wrapper
around the ''HBaseAdmin'' and ''HTable'' java classes that can be found at ''${HBASE_HOME}/bin/HBase.rb''
-- and then starts up a subclass of IRB, named HIRB (IRB is the name of the interactive Ruby
interpreter; for an untainted irb experience, type 'irb' on a system that has ruby installed).
 The subclassing is done to alter slightly some of the usual IRB behaviors.  For instance,
every command invocation returns a result and the result is printed to the terminal even if
the result is nil.  The subclass intercepts nil emissions and just suppresses them. ''
- 
- Anything you can do in irb, or at least in its JRuby equivalent, ''jirb'', you should be
able to do in HBase Shell.
- 
- == Scripting ==
- You can pass scripts to the HBase Shell by doing the following:
- 
- {{{
- durruti:~ stack$ ${HBASE_HOME}/bin/hbase shell PATH_TO_SCRIPT
- }}}
- 
- Your script can lean on the methods provided by the HBase Shell.
- 
- For more control, you may prefer manipulating HTable and HBaseAdmin methods directly.  For
example, if you would do your own formatting or you are storing structures that are mangled
when manipulated in HBase Shell.  In this case, you might pass your scripts directly to JRuby
by doing:
- 
- {{{
- durruti:~ stack$ ${HBASE_HOME}/bin/hbase org.jruby.Main PATH_TO_SCRIPT
- }}}
- 
- For examples writing straight ruby manhandling hbase client instances, see the scripts on
this page: [[Hbase/JRuby]] (Ignore the sections that have you fetching the jruby jar and the
prefacing your scripts with the '#!' bang magic).
- 
- == Useful Tricks ==
- === irbrc ===
- Create an ''.irbrc'' file for yourself in your home directory.  Add HBase Shell customizations.
 A useful one is command history:
- 
- {{{
- durruti:~ stack$ more .irbrc
- require 'irb/ext/save-history'
- IRB.conf[:SAVE_HISTORY] = 100
- IRB.conf[:HISTORY_FILE] = "#{ENV['HOME']}/.irb-save-history"
- }}}
- 
- === Log date to timestamp ===
- 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, do: {{{
- 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 hbase log format is a pain messing with SimpleDateFormat.
- 

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