PCDE Practice Question: Manage a solution that can span multiple database technologies
A Cloud Memorystore for Redis instance is running out of memory. The team wants to automatically remove the least recently used keys when memory is full. Which eviction policy should they configure?
⚠ Common exam trap
A common pitfall is confusing volatile-lru (only keys with TTL) with allkeys-lru (all keys), leading candidates to choose volatile-lru when the requirement is to consider all keys.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
allkeys-lru
The `allkeys-lru` eviction policy is correct because it applies the LRU (Least Recently Used) algorithm to all keys in the Redis instance, not just those with an expiry set. This ensures that when memory is full, the least recently accessed keys are automatically removed, regardless of whether they have a TTL, which directly meets the requirement to free memory without manual intervention.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
volatile-lru
Why it's wrong here
Evicts only keys with TTL set.
- ✗
volatile-ttl
Why it's wrong here
Evicts keys with shortest TTL.
- ✗
noeviction
Why it's wrong here
Does not evict; returns errors.
- ✓
allkeys-lru
Why this is correct
Evicts least recently used keys from all keys.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This PCDE practice question is part of Courseiva's free Google Cloud certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the PCDE exam.