PCDE Plan and manage database infrastructure Practice Question
This PCDE practice question tests your understanding of plan and manage database infrastructure. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 company needs to store time-series sensor data with high write throughput (millions of writes per second) and low latency reads. Which database service should they choose?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Cloud Bigtable
Cloud Bigtable is a fully managed, scalable NoSQL database designed for large analytical and operational workloads, handling millions of writes per second with consistent low-latency reads. It uses a distributed, replicated SSTable storage engine and is optimized for time-series data, making it ideal for high-throughput sensor ingestion.
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.
✓
Cloud Bigtable
Why this is correct
Bigtable is optimized for high write throughput and low-latency reads, ideal for time-series data.
Related concept
Read the scenario before looking for a memorised answer.
✗
Cloud SQL
Why it's wrong here
Cloud SQL has limited throughput and is not designed for time-series at this scale.
✗
Firestore
Why it's wrong here
Firestore is designed for mobile/web applications with moderate throughput, not millions of writes per second.
✗
Cloud Spanner
Why it's wrong here
Spanner is a globally distributed relational database, but its write throughput is not as high as Bigtable for simple time-series.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the misconception that Cloud Spanner's global scalability makes it suitable for all high-throughput workloads, but candidates overlook its transactional overhead and cost, which make it inappropriate for simple time-series writes at millions per second.
Detailed technical explanation
How to think about this question
Cloud Bigtable achieves high throughput by automatically sharding data into tablets, each served by a separate node, and using a distributed commit log (HDFS-based) for durability. It supports the HBase API and can ingest data from streaming sources like Pub/Sub or Dataflow, with read latencies typically under 10 ms for point lookups. A real-world scenario is IoT sensor data from millions of devices, where Bigtable handles the write spike and enables real-time dashboards via queries on row keys.
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 media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
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.
Plan and manage database infrastructure — This question tests Plan and manage database infrastructure — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Cloud Bigtable — Cloud Bigtable is a fully managed, scalable NoSQL database designed for large analytical and operational workloads, handling millions of writes per second with consistent low-latency reads. It uses a distributed, replicated SSTable storage engine and is optimized for time-series data, making it ideal for high-throughput sensor ingestion.
What should I do if I get this PCDE question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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