Design innovative, scalable, and highly available cloud database solutions →mediumMultiple ChoiceObjective-mapped
PCDE Practice Question: Design innovative, scalable, and highly available cloud database solutions
A company is using Cloud SQL for MySQL for its OLTP workload. They want to run complex analytical queries on the same data without impacting transactional performance. The analytical queries involve large scans and joins. What is the recommended approach?
⚠ Common exam trap
Google often tests the misconception that a read replica can handle analytical workloads without impact, but the trap here is that read replicas still run the same MySQL engine and share storage I/O, making them unsuitable for large scans and joins that would degrade performance for all queries on that replica.
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
✓
Export the data to BigQuery periodically and run analytical queries there
BigQuery is a serverless, highly scalable data warehouse designed for analytical queries on large datasets. By exporting data from Cloud SQL (OLTP) to BigQuery, you isolate the analytical workload from the transactional database, preventing resource contention and performance degradation on the primary instance. This separation of concerns is the recommended pattern for running complex scans and joins without impacting OLTP performance.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Export the data to BigQuery periodically and run analytical queries there
Why this is correct
BigQuery is designed for complex analytics; periodic exports ensure no impact on the OLTP instance.
- ✗
Enable MySQL Query Cache to speed up analytical queries on the primary instance
Why it's wrong here
Query cache is limited and not suitable for large scans; it also impacts write performance.
- ✗
Use Cloud Spanner to handle both OLTP and analytics with interleaved tables
Why it's wrong here
Spanner is not optimized for complex analytical queries; it is transactional.
- ✗
Create a Cloud SQL read replica and route analytical queries to it
Why it's wrong here
Read replicas help with read offload, but complex analytical queries can still degrade replica performance.
Quick reference
Cloud Service Model Comparison
| Model | You Manage | Provider Manages | Examples |
|---|---|---|---|
| IaaS | OS, runtime, apps, data | Hardware, hypervisor, networking | EC2, Azure VMs, GCP Compute Engine |
| PaaS | Apps and data | OS, runtime, middleware, hardware | Elastic Beanstalk, Azure App Service |
| SaaS | Data and settings only | Everything else | Microsoft 365, Salesforce, Workday |
| FaaS / Serverless | Function code only | Infra, scaling, runtime | Lambda, Azure Functions, Cloud Run |
| CaaS | Containers and apps | Kubernetes, OS, hardware | EKS, AKS, GKE |
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Same concept, more angles
1 more way this is tested on PCDE
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A company uses Cloud SQL for MySQL and wants to run complex analytical queries on the same data without affecting OLTP performance. They need a solution with minimal data movement and low operational overhead. Which approach should they take?
medium- A.Migrate to Cloud Spanner
- B.Export data to BigQuery periodically
- C.Set up a Cloud SQL read replica and run analytical queries on it
- ✓ D.Use AlloyDB for PostgreSQL with its columnar engine
Why D: AlloyDB is a PostgreSQL-compatible database that includes a columnar engine for analytical queries, providing HTAP capabilities with minimal performance impact on OLTP. BigQuery requires exporting data, which adds latency and overhead. Read replicas still run on MySQL engines optimized for OLTP. Spanner is overkill and requires migration. AlloyDB is the best fit for HTAP.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.