PDE Designing Data Processing Systems Practice Question
A startup is building a data lake on Google Cloud. They need to store raw JSON logs in a cost-effective manner and later query them using SQL with minimal transformation. The logs are infrequently accessed but must be retained for 7 years for compliance. Which storage solution should they use?
⚠ Common exam trap
The trap here is choosing Nearline or Coldline for 7-year retention when Archive is specifically designed for the lowest-cost, long-term storage.
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 Storage with Archive storage class and BigQuery external tables.
Archive storage in Cloud Storage is the most cost-effective for long-term retention of infrequently accessed data. BigQuery external tables enable SQL querying of JSON logs directly from Cloud Storage without loading or transformation. This meets the cost, retention, and query requirements. The other options use higher-cost storage or databases not optimized for this 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.
- ✗
Cloud Bigtable with a column family for JSON logs and a HBase client for querying.
Why it's wrong here
Bigtable is a NoSQL database optimized for high-throughput reads and writes, not for cost-effective long-term storage of infrequently accessed data. It does not support SQL querying natively and would require additional tools. The cost of running a Bigtable cluster for 7 years would be significantly higher than Archive storage.
- ✗
Cloud SQL for PostgreSQL with JSONB columns and scheduled exports to Cloud Storage.
Why it's wrong here
Cloud SQL is a relational database designed for transactional workloads, not for storing large volumes of raw logs cost-effectively. It supports JSONB and SQL, but the cost of running an instance for 7 years is prohibitive compared to Archive storage. Scheduled exports add complexity and do not eliminate the need for a cost-effective primary storage.
- ✓
Cloud Storage with Archive storage class and BigQuery external tables.
Why this is correct
Archive storage is the lowest-cost option for long-term retention and is ideal for data accessed less than once a year. BigQuery external tables allow querying JSON data directly from Cloud Storage without loading, satisfying the SQL query requirement with minimal transformation. This combination is both cost-effective and functional for infrequent access over 7 years.
- ✗
Cloud Storage with Nearline storage class and BigQuery external tables.
Why it's wrong here
Nearline storage is cost-effective for data accessed less than once a month, but for infrequently accessed data retained for years, Coldline or Archive is more cost-effective. BigQuery external tables can query JSON, but Nearline is not the most economical for long-term retention. This option does not optimize cost for the 7-year retention requirement.
Go deeper
Related to this question
About these practice questions
One of 747 original PDE practice questions on Courseiva, each with a full explanation and wrong-answer analysis — not exam dumps or protected exam content. Learn why practice questions differ from exam dumps →
JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Google Cloud exam blueprint
This PDE 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 PDE exam.