HBase API for Administration

Question 1

What language does the HBase Shell use?

Answer 1

JRuby

Question 2

What is the HBase Shell?

Answer 2

• It is a command line interface used to call Hbase. - Wraps Java client calls in Ruby
• Allows Ruby syntax
• Makes parameters usage a little different that most shells.
• Command parameters are single quoted (‘)

Question 3

How do you start the hbase shell?

Answer 3

hbase shell

Question 4

What is the command to see help?

Answer 4

help

Question 5

What is the command to see the status of Hbase?

Answer 5

status

Question 6

What is reported in the status command?

Answer 6

The number of servers, the number of dead servers and the average load

Question 7

What is the command to get the version?

Answer 7

version

Question 8

What is the hash rocket symbol?

Answer 8

=>

Question 9

What is the syntax for creating a table using the shell command?

Answer 9

create ‘t1’, {NAME => ‘cf1’}
create ‘t1’, {NAME => ‘cf1’, VERSION => 5}
create ‘t1’, {NAME => ‘cf1’}, {NAME => ‘cf2’}

or short hand
create ‘t1’,’cf1’,’cf2’

Question 10

What modes are supported by Hbase shell?

Answer 10

interactive and batch

Question 11

When creating a table, what needs to be defined?

Answer 11

The table name and the column family.

Question 12

Does HBase have a concept of multiple database?

Answer 12

No

Question 13

True or False, Every table must have at least one column family when creating the table?

Answer 13

True

Question 14

When using the JAVA API you need to convert all everything to what?

Answer 14

A byte array

Question 15

What class contains methods for converting primitives and Strings to byte arrays?

Answer 15

A utility class called Bytes

Question 16

Using the Java API what is the first line of any class that reads the connection information for HBase?

Answer 16

Configuration configuration = new Configuration()

Question 17

When you want to use the Administration API what class do you instantiate?

Answer 17

HBaseAdmin admin = new HBaseAdmin(configuration);

Question 18

If you wanted to create a new table using the Java API what would the code look like to do that

Answer 18

HTableDescriptor descriptor = new HTableDescriptor(Bytes.toBytes(“t1”));
HColumnDescriptor column = new HColumnDescriptor(Bytes.toBytes(“cf1”));
descriptor.addFamily(column);
admin.createTable(descriptor);
admin.close();

Question 19

What does the Java Configuration object do?

Answer 19

Reads in the Hadoop and HBase configuration files

Question 20

In the HBase shell, how do you get a list of the tables

Answer 20

list

Question 21

In the HBase Java API, how do you get a list of the tables?

Answer 21

HTableDescriptor[] tables = admin.listTables();

Question 22

In HBase shell, waht is the syntax for getting the details about a table?

Answer 22

describe ‘tablename’

Question 23

In HBase Java API, what is the syntax for getting the details about a table

Answer 23

HTableDescriptor[] description = admin.getTableDescriptor(Bytes.toBytes(“tablename”));

Question 24

In HBase shell, how do you disable a table?

Answer 24

disable ‘tablename’

Question 25

What happens when you disable a table

Answer 25

- Allows various maintenance commands to be run - Prevents all client access - Allows you to alter a table - Takes several minutes for a table to be disabled

Question 26

In the Java API, how do you disable a table?

Answer 26

admin.disableTable("tablename");

Question 27

How do you take a table out of maintenance mode in Hbase shell?

Answer 27

enable 'tablename'

Question 28

Using the Java API, how to you take a table out of maintenance mode?

Answer 28

admin.enableTable("tablename");

Question 29

Can you alter a table after if has been created?

Answer 29

Yes, it needs to be in maintenance mode (or disabled) in order to do that

Question 30

How do you delete a table from Hbase using the shell command?

Answer 30

disable 'tablename' | drop 'tablename'

Question 31

How do you truncate a table in HBase shell?

Answer 31

truncate 'tablename'

Question 32

Using hbase shell, how do you add a new column family to a table

Answer 32

disable 'tablename' alter 'tablename', NAME => 'newColFamily' enable 'tablename'

Question 33

Using hbase shell, how do you permanently delete an existing column family

Answer 33

disable 'tablename' alter 'tablename', NAME => 'colFamily', METHOD => 'delete' enable 'tablename'

Question 34

Using hbase shell, how do you modify an existing column family to have 5 versions

Answer 34

disable 'tablename' alter 'tablename', NAME => 'colFamily', VERSIONS => 5 enable 'tablename'