- A
Add a hash prefix to the primary key by salting the player ID.
Salting distributes writes evenly.
- B
Change primary key to use a combination of timestamp and player ID.
Why wrong: Timestamps are monotonically increasing, still causing hotspots.
- C
Convert the primary key to a UUID stored as bytes.
Why wrong: UUIDs are random, which helps, but the question asks about hash prefix; also UUIDs are large.
- D
Create a parent-child interleaved table structure.
Why wrong: Interleaving affects locality but does not fix a monotonically increasing primary key hotspot.
Question 774 of 1,000
PCDOE Design and Plan Database Solutions Practice Question
This PCDOE practice question tests your understanding of design and plan database solutions. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A gaming company uses Cloud Spanner to store player profiles and game state. The database has a table 'Players' with a monotonically increasing integer primary key. During a global launch event, write latency spikes and throughput drops. The issue is traced to hotspotting. Which schema change should the team implement to mitigate this?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"primary"Why it matters: Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.
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 hash prefix to the primary key by salting the player ID.
Option A is correct because adding a hash prefix to the monotonically increasing integer primary key distributes writes across multiple Cloud Spanner splits, preventing hotspotting. Without this, sequential player IDs cause all new inserts to target the same split, leading to write contention and throughput drops during high-volume events like a global launch.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Add a hash prefix to the primary key by salting the player ID.
Why this is correct
Salting distributes writes evenly.
Clue confirmation
The clue word "primary" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Change primary key to use a combination of timestamp and player ID.
Why it's wrong here
Timestamps are monotonically increasing, still causing hotspots.
- ✗
Convert the primary key to a UUID stored as bytes.
Why it's wrong here
UUIDs are random, which helps, but the question asks about hash prefix; also UUIDs are large.
- ✗
Create a parent-child interleaved table structure.
Why it's wrong here
Interleaving affects locality but does not fix a monotonically increasing primary key hotspot.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that any random key (like a UUID) automatically solves hotspotting, but in Cloud Spanner, the key's distribution across splits depends on the key's prefix—without explicit salting or hashing, even UUIDs can cluster if the leading bytes are not random enough.
Detailed technical explanation
How to think about this question
Cloud Spanner uses split-based architecture where each split is a contiguous range of primary key values. A monotonically increasing key causes all new writes to land on the same split (the 'last' split), creating a single point of contention. Adding a hash prefix (e.g., a 4-byte hash of the player ID) randomizes the key distribution across splits, allowing parallel writes. The hash prefix should be chosen to ensure uniform distribution; a common approach is to use a modulo operation on a hash of the original key to generate a prefix that spreads writes evenly.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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FAQ
Questions learners often ask
What does this PCDOE question test?
Design and Plan Database Solutions — This question tests Design and Plan Database Solutions — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Add a hash prefix to the primary key by salting the player ID. — Option A is correct because adding a hash prefix to the monotonically increasing integer primary key distributes writes across multiple Cloud Spanner splits, preventing hotspotting. Without this, sequential player IDs cause all new inserts to target the same split, leading to write contention and throughput drops during high-volume events like a global launch.
What should I do if I get this PCDOE question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "primary". Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
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Last reviewed: Jul 4, 2026
This PCDOE 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 PCDOE exam.
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