PDE Storing the Data Practice Question
A data engineer needs to store transactional data for an e-commerce application that requires ACID compliance, automatic failover, and point-in-time recovery. The expected throughput is a few thousand transactions per second. Which Google Cloud storage option should they choose?
⚠ Common exam trap
Candidates often choose Cloud Spanner for any ACID requirement, overlooking that Cloud SQL is the cost-effective and simpler choice for single-region transactional workloads with moderate throughput.
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
✓
Cloud SQL
Cloud SQL is the correct choice because it provides full ACID compliance, automated failover with high availability configurations, and point-in-time recovery via binary log replay. It supports up to several thousand transactions per second with appropriate machine sizing, making it suitable for this e-commerce workload.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Firestore
Why it's wrong here
Firestore is a document database that supports transactions but is not relational and best for mobile/web apps.
- ✗
Cloud Bigtable
Why it's wrong here
Bigtable is a NoSQL database that does not support ACID transactions across rows.
- ✓
Cloud SQL
Why this is correct
Cloud SQL provides ACID compliance, high availability, and PITR for moderate OLTP workloads.
- ✗
Cloud Spanner
Why it's wrong here
Cloud Spanner, whilst offering ACID compliance, automatic failover, and point-in-time recovery, is engineered for globally distributed, petabyte-scale transactional workloads demanding extremely high throughput, often millions of transactions per second. For a scenario specifying only "a few thousand transactions per second", its immense global scalability and associated operational complexity are excessive. It would be the correct choice if the application required strong transactional consistency across multiple continents with significantly higher, globally distributed throughput demands.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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