SUNION, SINTER, SDIFF set operations in Redis - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ query_result

intermediate

What is the result of SUNION on two sets?

Given two Redis sets:

Set A contains: {"apple", "banana", "cherry"}
Set B contains: {"banana", "date", "fig"}

What is the result of SUNION A B?

Redis

SADD A apple banana cherry
SADD B banana date fig
SUNION A B

A ["banana"]

B ["apple", "banana", "cherry"]

C ["apple", "banana", "cherry", "date", "fig"]

D ["date", "fig"]

💡 Hint

SUNION returns all unique members from both sets combined.

SUNION combines all unique elements from both sets. Since 'banana' is in both, it appears once. The result includes all unique fruits from both sets.

❓ query_result

intermediate

What does SINTER return for overlapping sets?

Given two Redis sets:

Set X contains: {"red", "blue", "green"}
Set Y contains: {"blue", "yellow", "green"}

What is the output of SINTER X Y?

Redis

SADD X red blue green
SADD Y blue yellow green
SINTER X Y

A ["blue", "green"]

B ["red", "yellow"]

C ["red", "blue", "green", "yellow"]

D []

💡 Hint

SINTER returns only members present in both sets.

SINTER returns the intersection of the sets, which are the elements present in both X and Y: blue and green.

❓ query_result

advanced

What is the output of SDIFF with three sets?

Given three Redis sets:

Set M contains: {"cat", "dog", "rabbit"}
Set N contains: {"dog", "hamster"}
Set O contains: {"rabbit", "parrot"}

What is the result of SDIFF M N O?

Redis

SADD M cat dog rabbit
SADD N dog hamster
SADD O rabbit parrot
SDIFF M N O

A ["rabbit"]

B ["dog", "cat"]

C ["hamster", "parrot"]

D ["cat"]

💡 Hint

SDIFF returns members in the first set that are not in any of the other sets.

SDIFF returns elements in M that are not in N or O. 'cat' is only in M, so it is returned.

🧠 Conceptual

advanced

Which Redis command would you use to find common elements between sets?

You want to find elements that exist in all given Redis sets. Which command should you use?

A SINTER

B SDIFF

C SUNION

D SMEMBERS

💡 Hint

Think about which command returns only shared members.

SINTER returns the intersection of sets, i.e., elements common to all sets.

📝 Syntax

expert

Identify the syntax error in this Redis command usage

Consider the following Redis command:

SDIFFSET myset otherset

What is wrong with this command?

A The command requires only one key, but two are given.

B The command name is incorrect; it should be SDIFFSTORE.

C The command should be SUNIONSET instead of SDIFFSET.

D The command is correct and will run without errors.

💡 Hint

Check the exact spelling of Redis commands for set operations.

The correct command to store the difference of sets is SDIFFSTORE, not SDIFFSET.