Design innovative, scalable, and highly available cloud database solutions →mediumMultiple SelectObjective-mapped
PCDE Practice Question: Design innovative, scalable, and highly available cloud database solutions
A data pipeline writes 10 TB of streaming data daily into Bigtable. The row key is based on the device ID and timestamp in reverse order. Recent data is queried most frequently. Which three design choices optimize performance and cost? (Choose THREE.)
⚠ Common exam trap
The Google Cloud Professional Data Engineer exam often tests the misconception that HDD is acceptable for cost savings in high-throughput streaming workloads, ignoring the latency requirements for frequent recent data queries, and that a design choice already implemented (like reverse timestamp) can be selected again as an optimization.
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
✓
Use a single cluster with SSD storage.
A single cluster with SSD storage provides low-latency access for frequently queried recent data, which is critical for streaming workloads. SSDs offer consistent single-digit millisecond latency, while HDDs would introduce higher latency unsuitable for real-time queries. This balances performance and cost for the described use case.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Use HDD storage to reduce cost per GB.
Why it's wrong here
HDD has higher latency and lower IOPS; not suitable for high performance.
- ✓
Use a single cluster with SSD storage.
Why this is correct
SSD provides low latency; single cluster reduces cost.
- ✗
Use reverse timestamp to make recent data first.
Why it's wrong here
Already in use; not an additional optimization.
- ✓
Pre-split the table to avoid write hotspotting during initial load.
Why this is correct
Pre-splitting ensures even distribution.
- ✓
Enable compression on column families to reduce storage footprint.
Why this is correct
Compression reduces costs.
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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.