Eviction policies (LRU, LFU, random) in Redis - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to set the eviction policy to Least Recently Used (LRU) in Redis configuration.

Redis

CONFIG SET maxmemory-policy [1]

Drag options to blanks, or click blank then click option'

Anoeviction

Bvolatile-lfu

Callkeys-lru

Drandom

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing 'volatile-lfu' which is for Least Frequently Used but only on volatile keys.

Using 'noeviction' which disables eviction.

Selecting 'random' which evicts keys randomly.

The allkeys-lru policy evicts the least recently used keys when memory is full.

2fill in blank

medium

Complete the code to set the eviction policy to Least Frequently Used (LFU) for volatile keys only.

Redis

CONFIG SET maxmemory-policy [1]

Drag options to blanks, or click blank then click option'

Avolatile-lru

Ballkeys-random

Callkeys-lfu

Dvolatile-lfu

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing 'allkeys-lfu' which applies LFU to all keys, not just volatile ones.

Selecting 'volatile-lru' which is LRU, not LFU.

Using 'allkeys-random' which evicts keys randomly.

The volatile-lfu policy evicts the least frequently used keys but only those with an expiration set.

3fill in blank

hard

Fix the error in the command to set a random eviction policy.

Redis

CONFIG SET maxmemory-policy [1]

Drag options to blanks, or click blank then click option'

Arandom

Ballkeys-random

Cvolatile-random

Drandom-eviction

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'random' alone which is not a valid policy name.

Choosing 'random-eviction' which is not recognized.

Selecting 'volatile-random' which only evicts volatile keys.

The correct policy name for random eviction of all keys is allkeys-random.

4fill in blank

hard

Fill both blanks to set the max memory to 100mb and eviction policy to allkeys-lfu.

Redis

CONFIG SET maxmemory [1]
CONFIG SET maxmemory-policy [2]

Drag options to blanks, or click blank then click option'

A100mb

Ballkeys-lfu

Cvolatile-lru

D50mb

Attempts:

3 left

💡 Hint

Common Mistakes

Using '50mb' instead of '100mb' for maxmemory.

Choosing 'volatile-lru' which is a different eviction policy.

Setting maxmemory to 100mb limits Redis memory usage, and allkeys-lfu evicts least frequently used keys from all keys.

5fill in blank

hard

Fill all three blanks to configure Redis to use 200mb max memory, volatile-lru eviction policy, and set a key expiration of 60 seconds.

Redis

CONFIG SET maxmemory [1]
CONFIG SET maxmemory-policy [2]
EXPIRE mykey [3]

Drag options to blanks, or click blank then click option'

Avolatile-lru

B60

C200mb

Dallkeys-random

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up eviction policies like choosing 'allkeys-random' instead of 'volatile-lru'.

Setting expiration time in wrong units.

We set maxmemory to 200mb, eviction policy to volatile-lru which evicts least recently used keys with expiration, and set expiration of 60 seconds on 'mykey'.