Operations using HBase Shell

Starting with HBase Shell Commands

2.1 HBase shell commands
HBase shell provide the commands which are used to communicate with hbase.

General Commands

• whoami: It gives the information about the user.

hbase> whoami

• status: It gives the status of HBase. Its syntax is as follows:

hbase> status

• table_help: It gives help for table-reference commands. Its syntax is as follows:-

hbase> table_help

• version: It gives  the version of HBase being used. Its syntax is as follows:

hbase> version

Data Definition Language
These are the commands that operate on the tables in HBase.

• create– It is used to creates a table.

create ‘<table name>’,’<column family>’

• disable– It is used to disables a table.

Hbase>disable ‘table name’

• is_disabled– It verifies that  whether a table is disabled.

hbase> is_disabled 'table name'

• list– It is used to lists all the table.

hbase> list

• enable–It is used to enables a table.

hbase>enable ‘table name’

• is_enabled– It verifies that whether a table is enabled.

hbase> is_enabled 'table name'

• exit – It is used to exit the shell.

hbase>exit

• alter– This command is used to alter the table

hbase>alter ‘table name’, 'conditions'

• exists– It verifies that whether a table exists.

hbase>exists ‘table name’

• describe– It gives the description of a table.

hbase> describe 'table name'

• drop– It drops a table from HBase. Drop means complete deletion of table. For this first disable the table then drop it.

hbase> disable ‘table name’
hbase> drop ‘table name’

• drop_all– It is used to drop the tables matching the ‘regex’ given in the command.

hbase>drop_all regex;

Regex is the term which specify the table name like if you want to delete those table which are start from f then regex will be f.*
Java Admin API– Java gives an Admin API to achieve DDL functionalities through programming. Package apache.hadoop.hbase.client contains two classes, HBaseAdmin and HTableDescriptor that provide DDL functionalities.

Data manipulation language

• put– It is used to put a cell value at a specified column in a specified row in a particular table. Using this command, we can insert rows into a table. Its syntax is as follows:

hbase>put ’<table name>’,’row’,’<columnfamily:columnname>’,’<value>’

• delete– It is used to delete a cell value in a table.

hbase>delete ‘<table name>’, ‘<row>’, ‘<column name >’, ‘<time_stamp>’

• deleteall– It deletes all the cells in a given row.

hbase>deleteall ‘<table name>’, ‘<row>’

• get– It is used to read the contents of row or a cell.

hbase>get ’<table name>’,’row’

• count– It counts and returns the number of rows in a specified

hbase>count ‘<table name>’

• scan– It is used to scan and  then return the table data.

hbase>scan ‘<table name>’

• truncate– It is used to disables, drop, and recreate a specified table.

hbase>truncate 'table name'

• Java client API-Java provides a client API to obtain DML functionalities. org.apache.hadoop.hbase.client package has HTable Put and Get are the classes which are used to perform CRUD(create, retrieve, update, delete) operation

2. 2 Commands for Security:-
Following commands are used to provide the security of the database from unauthorized access.

• grant – It is used to give specific rights such write, execute, read and admin on a table to a particular user.

hbase>grant <username> <permissions> [<tablename> [<column _family> [<column; qualifier>]]

• user_permission – It gives the list of all the permissions for a specified table.

hbase>user_permission ‘tablename’

• revoke – It is used to revoke a user’s access rights of a table. Its syntax is as follows:

hbase> revoke <user>