GETRANGE and SETRANGE in Redis - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ query_result

intermediate

What is the output of GETRANGE after SETRANGE?

Given a Redis key mykey with initial value "Hello World", what will be the result of GETRANGE mykey 6 10 after running SETRANGE mykey 6 "Redis"?

Redis

SET mykey "Hello World"
SETRANGE mykey 6 "Redis"
GETRANGE mykey 6 10

A "World"

B "Redis"

C "Redisorld"

D "Hello"

💡 Hint

Remember SETRANGE replaces part of the string starting at the given offset.

The SETRANGE command replaces the substring starting at index 6 with "Redis", so the string becomes "Hello Redis". Then GETRANGE from 6 to 10 returns "Redis".

❓ query_result

intermediate

What does GETRANGE return for out-of-bound indexes?

If the Redis key msg has value "OpenAI", what is the result of GETRANGE msg 3 10?

Redis

SET msg "OpenAI"
GETRANGE msg 3 10

A "nAI"

B "nAI\u0000\u0000\u0000\u0000"

C "OpenAI"

D ""

💡 Hint

GETRANGE returns substring up to the end if end index is beyond string length.

The string "OpenAI" has length 6. GETRANGE from index 3 to 10 returns substring from 3 to end, which is "nAI".

📝 Syntax

advanced

Which SETRANGE command is syntactically correct?

Choose the correct syntax to replace part of the string stored at key data starting at offset 4 with "Test".

A SETRANGE data "4" "Test"

B SETRANGE data 4 Test

C SETRANGE data 4 "Test"

D SETRANGE data 4 'Test'

💡 Hint

The offset must be an integer and the value a string enclosed in quotes.

SETRANGE requires the offset as an integer and the value as a string. Option C correctly uses integer 4 and string "Test".

❓ optimization

advanced

Efficiently update a substring in a large Redis string

You have a large string stored in Redis key bigtext. You want to replace characters from position 1000 to 1004 with "Hello". Which command is the most efficient?

A SETRANGE bigtext 1000 "Hello"

B

GET bigtext
Modify substring in client
SET bigtext modified_string

C APPEND bigtext "Hello"

D

GETRANGE bigtext 0 999
APPEND "Hello"

💡 Hint

SETRANGE modifies the string in place without transferring the whole string.

SETRANGE modifies the string directly on the server at the specified offset, avoiding large data transfer.

🧠 Conceptual

expert

What happens if SETRANGE offset is beyond current string length?

If the Redis key key1 has value "abc", what is the result of SETRANGE key1 5 "xyz" followed by GET key1?

Redis

SET key1 "abc"
SETRANGE key1 5 "xyz"
GET key1

A "abc xyz"

B Error: offset out of range

C "abcxyz"

D "abc\u0000\u0000xyz"

💡 Hint

SETRANGE pads with zero-bytes if offset is beyond string length.

SETRANGE pads the string with zero-bytes (\u0000) up to the offset before inserting the new substring.