Design innovative, scalable, and highly available cloud database solutions →easyMultiple SelectObjective-mapped
PCDE Practice Question: Design innovative, scalable, and highly available cloud database solutions
A retail company is designing a new inventory management system on Cloud Spanner. They need to ensure high write throughput for order processing. Which two schema design practices help avoid write hotspots? (Choose TWO.)
⚠ Common exam trap
Candidates often mistakenly think that secondary indexes or foreign keys improve write throughput in Cloud Spanner, but these features only assist reads or data integrity, not write distribution. The key is to avoid monotonically increasing primary keys and use hash prefixes to distribute writes.
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
✓
Avoid using a monotonically increasing primary key.
Monotonically increasing primary keys (e.g., auto-increment integers or timestamps) cause all new writes to be directed to the same tablet server, creating a hot spot. Cloud Spanner splits data by key range, so sequential keys concentrate load on a single split. Option E is correct because adding a hash prefix to the primary key distributes writes uniformly across splits, preventing any single node from becoming a bottleneck.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Create secondary indexes on frequently queried columns.
Why it's wrong here
Secondary indexes affect reads, not write distribution.
- ✓
Avoid using a monotonically increasing primary key.
Why this is correct
Monotonically increasing keys cause hotspotting.
- ✗
Store all data in a single table with no interleaving.
Why it's wrong here
Interleaving or not does not avoid hotspots.
- ✗
Use foreign keys to enforce referential integrity.
Why it's wrong here
Foreign keys do not influence write distribution.
- ✓
Add a hash prefix to the primary key to distribute writes.
Why this is correct
Salting prevents hotspotting.
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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.