To delete a table or change its settings, you need to first disable the table using the disable command. You can re-enable it using the enable command.

Given below is the syntax to disable a table:

disable ‘emp’

Example

Given below is an example that shows how to disable a table.

hbase(main):025:0> disable ’emp’

0 row(s) in 1.2760 seconds

Verification

After disabling the table, you can still sense its existence through list and exists commands. You cannot scan it. It will give you the subsequent error.

hbase(main):028:0> scan ’emp’

ROW COLUMN + CELL

ERROR: emp is disabled.

is_disabled

This command is employed to find whether a table is disabled. Its syntax is as follows.

hbase> is_disabled ‘table name’

The subsequent example verifies whether the table named emp is disabled. If it is disabled, it will return true and if not, it will return false.

hbase(main):031:0> is_disabled ’emp’

true

0 row(s) in 0.0440 seconds

disable_all

This command is employed to disable all the tables matching the given regex. The syntax for disable_all command is given below.

hbase> disable_all ‘r.*’

Suppose there are 5 tables in HBase, namely raja, rajani, rajendra, rajesh, and raju. The subsequent code will disable all the tables starting with raj.

hbase(main):002:07> disable_all ‘raj.*’

raja

rajani

rajendra

rajesh

raju

Disable the above 5 tables (y/n)?

5 tables successfully disabled

Disable a Table Using Java API

To verify whether a table is disabled, isTableDisabled() method is employed and to disable a table, disableTable() method is employed. These methods belong to the HBaseAdmin class. Follow the steps given below to disable a table.

Step 1

Instantiate HBaseAdmin class as shown below.

// Creating configuration object

Configuration conf = HBaseConfiguration.create();

// Creating HBaseAdmin object

HBaseAdmin admin = new HBaseAdmin(conf);

Step 2

Verify whether the table is disabled using isTableDisabled() method as shown below.

Boolean b = admin.isTableDisabled(“emp”);

Step 3

If the table is not disabled, disable it as shown below.

if(!b){

admin.disableTable(“emp”);

System.out.println(“Table disabled”);

}

Given below is the complete program to verify whether the table is disabled; if not, how to disable it.

import java.io.IOException;

import org.apache.hadoop.conf.Configuration;

import org.apache.hadoop.hbase.HBaseConfiguration;

import org.apache.hadoop.hbase.MasterNotRunningException;

import org.apache.hadoop.hbase.client.HBaseAdmin;

public class DisableTable{

public static void main(String args[]) throws MasterNotRunningException, IOException{

// Instantiating configuration class

Configuration conf = HBaseConfiguration.create();

// Instantiating HBaseAdmin class

HBaseAdmin admin = new HBaseAdmin(conf);

// Verifying weather the table is disabled

Boolean bool = admin.isTableDisabled(“emp”);

System.out.println(bool);

// Disabling the table using HBaseAdmin object

if(!bool){

admin.disableTable(“emp”);

System.out.println(“Table disabled”);

}

Compile and execute the above program as shown below.

$javac DisableTable.java

$java DsiableTable

The subsequent should be the output:

false

Table disabled

HBase – Enabling a Table

Enabling a Table using HBase Shell

Syntax to enable a table:

enable ‘emp’

Example

Given below is an example to enable a table.

hbase(main):005:0> enable ’emp’

0 row(s) in 0.4580 seconds

Verification

After enabling the table, scan it. If you can see the schema, your table is successfully enabled.

hbase(main):006:0> scan ’emp’

ROW COLUMN + CELL

1 column = personal data:city, timestamp = 1417516501, value = hyderabad

1 column = personal data:name, timestamp = 1417525058, value = ramu

1 column = professional data:designation, timestamp = 1417532601, value = manager

1 column = professional data:salary, timestamp = 1417524244109, value = 50000

2 column = personal data:city, timestamp = 1417524574905, value = chennai

2 column = personal data:name, timestamp = 1417524556125, value = ravi

2 column = professional data:designation, timestamp = 14175292204, value = sr:engg

2 column = professional data:salary, timestamp = 1417524604221, value = 30000

3 column = personal data:city, timestamp = 1417524681780, value = delhi

3 column = personal data:name, timestamp = 1417524672067, value = rajesh

3 column = professional data:designation, timestamp = 14175246987, value = jr:engg

3 column = professional data:salary, timestamp = 1417524702514, value = 25000

3 row(s) in 0.0400 seconds

is_enabled

This command is employed to find whether a table is enabled. Its syntax is as follows:

hbase> is_enabled ‘table name’

The subsequent code verifies whether the table named emp is enabled. If it is enabled, it will return true and if not, it will return false.

hbase(main):031:0> is_enabled ’emp’

true

0 row(s) in 0.0440 seconds

Enable a Table Using Java API

To verify whether a table is enabled, isTableEnabled() method is employed; and to enable a table, enableTable() method is employed. These methods belong to HBaseAdmin class. Follow the steps given below to enable a table.

Step1

Instantiate HBaseAdmin class as shown below.

// Creating configuration object

Configuration conf = HBaseConfiguration.create();

// Creating HBaseAdmin object

HBaseAdmin admin = new HBaseAdmin(conf);

Step 2

Verify whether the table is enabled using isTableEnabled() method as shown below.

Boolean bool = admin.isTableEnabled(“emp”);

Step 3

If the table is not disabled, disable it as shown below.

if(!bool){

admin.enableTable(“emp”);

System.out.println(“Table enabled”);

}

Given below is the complete program to verify whether the table is enabled and if it is not, then how to enable it.

import java.io.IOException;

import org.apache.hadoop.conf.Configuration;

import org.apache.hadoop.hbase.HBaseConfiguration;

import org.apache.hadoop.hbase.MasterNotRunningException;

import org.apache.hadoop.hbase.client.HBaseAdmin;

public class EnableTable{

public static void main(String args[]) throws MasterNotRunningException, IOException{

// Instantiating configuration class

Configuration conf = HBaseConfiguration.create();

// Instantiating HBaseAdmin class

HBaseAdmin admin = new HBaseAdmin(conf);

// Verifying whether the table is disabled

Boolean bool = admin.isTableEnabled(“emp”);

System.out.println(bool);

// Enabling the table using HBaseAdmin object

if(!bool){

admin.enableTable(“emp”);

System.out.println(“Table Enabled”);

}

Compile and execute the above program as shown below.

$javac EnableTable.java

$java EnableTable

The subsequent should be the output:

false

Table Enabled

So, this brings us to the end of blog. This Tecklearn ‘How to enable and disable a Table using HBase shell’ helps you with commonly asked questions if you are looking out for a job in HBase and No-SQL Database Domain.

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NoSQL Vs RDBMS
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Data Modelling
HDFS vs. HBase
HBase Use Cases

HBase Architecture and Components

HBase Architecture
Components of HBase Cluster

HBase Installation

Prerequisites for HBase Installation
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Programming in HBase

Create an Eclipse Project for HBase
Simple Table Creation from Java in HBase
HBase API
HBase Shell
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