Eviction policies (LRU, LFU, random) in Redis - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does LRU stand for in Redis eviction policies?

LRU stands for Least Recently Used. It removes the keys that have not been accessed for the longest time when memory is full.

beginner

Explain the LFU eviction policy in Redis.

LFU means Least Frequently Used. It removes keys that are used the least often, based on how many times they were accessed.

beginner

What happens when Redis uses the random eviction policy?

Redis randomly removes keys to free memory, without considering usage or frequency.

beginner

Why are eviction policies important in Redis?

Eviction policies help Redis manage limited memory by deciding which keys to remove when memory is full, keeping the system fast and stable.

intermediate

Which eviction policy would be best if you want to keep the most recently used data in Redis?

The LRU (Least Recently Used) policy is best because it removes the oldest unused data, keeping recent data available.

What does the LRU eviction policy remove in Redis?

A Keys that are the largest in size

B Keys that were least recently accessed

C Keys randomly chosen

D Keys that were most frequently accessed

LRU removes keys that have not been accessed for the longest time.

Which eviction policy removes keys based on how often they are used?

A LFU

B LRU

C Random

D FIFO

LFU removes keys that are used the least frequently.

If Redis uses the random eviction policy, which keys get removed?

A The largest keys

B The least frequently used keys

C The oldest keys

D Randomly selected keys

Random eviction removes keys without considering usage or age.

Why might you choose LRU over LFU in Redis?

A LRU is simpler and tracks recent usage, good for caching

B LRU removes keys randomly

C LFU removes the newest keys

D LFU is faster to compute

LRU tracks recent usage and is simpler, making it good for caching scenarios.

What is the main goal of eviction policies in Redis?

A To backup data automatically

B To increase disk space

C To manage memory by removing keys when full

D To encrypt stored keys

Eviction policies help Redis manage limited memory by removing keys when memory is full.

Describe how the LRU and LFU eviction policies differ in Redis.

Think about whether the policy tracks time or frequency of access.

Explain why Redis needs eviction policies and give an example of when one might be used.

Consider what happens when Redis runs out of memory.