CRUD operations in HBase in Hadoop - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this HBase shell command?

Consider the following HBase shell commands executed sequentially:

create 'students', 'info'
put 'students', 'row1', 'info:name', 'Alice'
put 'students', 'row1', 'info:age', '21'
get 'students', 'row1', 'info:name'

What will be the output of the get command?

Hadoop

create 'students', 'info'
put 'students', 'row1', 'info:name', 'Alice'
put 'students', 'row1', 'info:age', '21'
get 'students', 'row1', 'info:name'

A

COLUMN              CELL
 info:age            timestamp=..., value=21

B

COLUMN              CELL
 info:age            timestamp=..., value=Alice

C

COLUMN              CELL
 info:name           timestamp=..., value=21

D

COLUMN              CELL
 info:name           timestamp=..., value=Alice

💡 Hint

The get command retrieves the value of the specified column for the given row.

The get command fetches the value stored in the 'info:name' column for 'row1', which is 'Alice'.

❓ data_output

intermediate

How many rows remain after this delete operation?

Given a table 'employees' with rows 'emp1', 'emp2', and 'emp3', after running:

deleteall 'employees', 'emp2'

How many rows will remain in the table?

Hadoop

deleteall 'employees', 'emp2'

A 2

B 3

C 1

D 0

💡 Hint

The deleteall command removes all columns for the specified row.

Deleting all columns of 'emp2' removes that row, so only 'emp1' and 'emp3' remain.

🔧 Debug

advanced

Identify the error in this HBase shell command sequence

What error will occur when running this sequence?

create 'products', 'details'
put 'products', 'p1', 'details:name', 'Laptop'
put 'products', 'p1', 'details:price', 1200
get 'products', 'p1', 'details:price'

Hadoop

create 'products', 'details'
put 'products', 'p1', 'details:name', 'Laptop'
put 'products', 'p1', 'details:price', 1200
get 'products', 'p1', 'details:price'

A TypeError because 1200 is not a string

B No error; output shows price as '1200'

C SyntaxError due to missing quotes around 1200

D NullPointerException because 'products' table does not exist

💡 Hint

HBase shell converts numbers to strings automatically in put.

HBase shell treats all values as strings, so 1200 is stored as '1200' without error.

🚀 Application

advanced

Which command updates a cell value in HBase?

You want to change the value of the cell in row 'r1', column 'info:status' to 'active' in the 'users' table. Which command will do this?

A modify 'users', 'r1', 'info:status', 'active'

B update 'users', 'r1', 'info:status', 'active'

C put 'users', 'r1', 'info:status', 'active'

D set 'users', 'r1', 'info:status', 'active'

💡 Hint

HBase uses put to insert or update data.

The put command inserts or updates the value of a cell in HBase.

🧠 Conceptual

expert

What happens if you try to get a non-existent row in HBase?

If you run get 'orders', 'order999' but 'order999' does not exist in the 'orders' table, what will be the result?

Hadoop

get 'orders', 'order999'

A Returns an empty result with no columns

B Raises a KeyError exception

C Returns the last row in the table

D Returns null and stops the shell

💡 Hint

HBase returns empty results for missing rows instead of errors.

If the row does not exist, HBase returns an empty result without error.