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Operations using HBase Shell

 

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>

This blog will help you get a better understanding of Hbase!

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