Google PCA Practice Question: Analyze and optimize technical and business processes
An e-commerce platform uses Cloud Spanner for order processing. Recently, latency spikes have occurred during flash sales. The team suspects hot spots due to monotonically increasing order IDs. Which table design change would best solve this?
⚠ Common exam trap
Google Cloud often tests the misconception that secondary indexes or interleaved tables can fix write hot spots, when in reality only primary key distribution strategies (like hash prefixes) address the root cause of split-level contention.
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
✓
Add a random prefix to the order ID primary key.
Monotonically increasing primary keys (like sequential order IDs) cause hot spots in Cloud Spanner because all writes are directed to a single split (tablet), overwhelming that node. Adding a random prefix (e.g., a hash of the customer ID) distributes writes across multiple splits, eliminating the hot spot and reducing latency spikes during high-throughput flash sales.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Remove the primary key and let Spanner auto-generate it.
Why it's wrong here
Spanner requires a primary key; auto-generation would still be monotonically increasing.
- ✗
Use interleaved tables to store orders under customers.
Why it's wrong here
Interleaving doesn't solve key hotspotting.
- ✓
Add a random prefix to the order ID primary key.
Why this is correct
Randomizing the first part of the key distributes writes across splits.
- ✗
Create a secondary index on the timestamp column.
Why it's wrong here
Secondary indexes don't affect write distribution.
Go deeper
Related to this question
Learn chapter
Introduction to Google Cloud Platform
Key term
Spanner
Google Cloud's globally distributed, strongly consistent, and horizontally scalable database service designed for mission-critical, transactional workloads.
Key term
IDS
An IDS is a security system that monitors network or system traffic for suspicious activity and alerts administrators to potential threats, but does not actively block them.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This PCA 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 PCA exam.