Design innovative, scalable, and highly available cloud database solutions →hardMultiple ChoiceObjective-mapped
PCDE Practice Question: Design innovative, scalable, and highly available cloud database solutions
A financial services company uses Cloud Bigtable to store transaction data. The row key is constructed as customer_id reversed timestamp. The team wants to retrieve the most recent 100 transactions for a specific customer quickly. Which row key design principle is being used to optimize this query?
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
✓
Reverse timestamp
Reverse timestamp in the row key ensures that the most recent transactions for a given customer appear first when scanning rows with that customer prefix.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Reverse timestamp
Why this is correct
Reverse timestamp orders rows so that recent entries come first for a given customer.
- ✗
Field promotion
Why it's wrong here
Field promotion puts frequently filtered fields first; customer_id is already first.
- ✗
Salting
Why it's wrong here
Salting adds a hash prefix to distribute writes, not to order recent data first.
- ✗
Composite key
Why it's wrong here
Composite key is too generic; the specific technique is reverse timestamp.
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JA
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.