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GCP Database Decision Tree: How to Choose for PCA Exam

February 5, 2026 13 min read By GCP Architect Team

If there is one topic that defines the PCA exam, it's Database Selection. Google doesn't just want to know if you know the services—they want to know if you know when to use them. For a broader overview of exam success, see our top 10 PCA tips.

GCP Database Decision Tree Flowchart

Follow these questions to find your match:

1. Is your data structured or unstructured?

  • Unstructured (Files/Videos): Cloud Storage.
  • Structured/Semi-structured: Proceed to next question.

2. Is it for Analytics (OLAP) or Transactions (OLTP)?

  • Analytics (Big Data/SQL): BigQuery.
  • Transactions/Operational: Proceed to next question.

3. Do you need relational (SQL) or NoSQL?

  • Relational:
    • Normal scale/Single region: Cloud SQL.
    • Massive scale/Global/99.999% SLA: Cloud Spanner (Highly recommended for cases like Mountkirk Games).
  • NoSQL:
    • Document/Mobile/Web sync: Firestore.
    • High-throughput/Low-latency/Analytical-lite: Bigtable (Essential for TerramEarth IoT data).

Deep Dive: The SQL Choices

Service Key Strengths Max Scale
Cloud SQL Standard MySQL/Postgres, ease of use Up to 64TB
Cloud Spanner Horizontal scale, Strong Consistency Petabytes+

Frequently Asked Questions (FAQ)

What is the maximum size for Cloud SQL?

Cloud SQL currently supports up to 64TB of storage, making it suitable for most standard relational workloads.

When is Cloud Bigtable the right choice?

Bigtable is ideal for low-latency, high-throughput NoSQL workloads like IoT telemetry, financial trade history, or ad-tech data.

Does Google Cloud provide a graph database?

Yes, Google Cloud provides Managed Service for Apache Age (PostgreSQL extension) and integrates with partners like Neo4j for dedicated graph workloads.

Exam Cheat Sheet:
  • Firestore = Mobile apps / Catalogs.
  • Bigtable = IoT streams / Time series / Ads.
  • Spanner = Global Finance / Inventory.
  • BigQuery = Business Intelligence / Logs.

Built for Architect Success

Take a practice exam to see these decision trees in action with real-world scenarios.

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