Design innovative, scalable, and highly available cloud database solutions →mediumMultiple ChoiceObjective-mapped
PCDE Practice Question: Design innovative, scalable, and highly available cloud database solutions
An engineer is designing a Bigtable row key for global user events. They want to avoid hotspots and enable efficient queries by user_id and time range. Which row key design is best?
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
✓
hash(user_id) + timestamp
Using a hash of user_id ensures distribution, and appending timestamp enables range scans by time within a user's events.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
hash(user_id) + timestamp
Why this is correct
Hash prefix distributes writes, timestamp enables time-based queries.
- ✗
reverse(timestamp) + user_id
Why it's wrong here
Still hotspotting on timestamp prefix.
- ✗
user_id + timestamp
Why it's wrong here
If user_id is sequential, it may cause hotspots; better to hash.
- ✗
timestamp + user_id
Why it's wrong here
Timestamp first causes write hotspots.
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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.