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PCDE Practice Question: Design innovative, scalable, and highly available cloud database solutions
You need to design a Cloud Bigtable row key for a time-series application that records user activity. The most common queries filter by user_id and then by timestamp (most recent first). Which row key design is MOST appropriate?
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
✓
user_id#reverse_timestamp
For time-series with frequent queries filtering by user_id and recent data, the recommended design is to put user_id first and then use a reverse timestamp. This ensures data for a user is co-located and the latest data appears first when scanning.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
user_id#timestamp
Why it's wrong here
This co-locates by user_id but recent data is at the end, requiring a reverse scan.
- ✓
user_id#reverse_timestamp
Why this is correct
This ensures data for a user is together and the most recent entry comes first.
- ✗
reverse_timestamp#user_id
Why it's wrong here
This would co-locate by time, not user, so user-specific queries would scatter.
- ✗
timestamp#user_id
Why it's wrong here
This would co-locate by timestamp, not user_id, making user-specific queries inefficient.
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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.