- A
Use BigQuery federated queries with external tables for both Cloud SQL and Bigtable
Federated queries allow querying Cloud SQL and Bigtable in-place, no data movement.
- B
Use Dataflow to continuously stream both Cloud SQL and Bigtable data into a single BigQuery dataset
Why wrong: This moves data into BigQuery, not desired.
- C
Use Cloud Spanner as a unified database for both transactional and session data
Why wrong: Migrating to Spanner is a larger change and not required; does not avoid data movement.
- D
Use Datastream to replicate Cloud SQL data to BigQuery, then join with Bigtable data using BigQuery's Bigtable external table
Why wrong: This moves data to BigQuery, violating the 'avoid moving data' requirement.
Question 676 of 980
PCD Practice Question: Manage a Solution that Can Span Multiple Database Systems
This PCD practice question tests your understanding of manage a solution that can span multiple database systems. 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.
An e-commerce application uses Cloud SQL for transactional data and Cloud Bigtable for user session logs. A new requirement demands real-time analytics that joins order data with session behavior. The team wants to avoid moving data into a separate data warehouse. Which approach should they take?
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
✓
Use BigQuery federated queries with external tables for both Cloud SQL and Bigtable
BigQuery federated queries allow you to query data in Cloud SQL and Cloud Bigtable directly using external tables, without moving the data. This approach meets the real-time analytics requirement by joining order data (Cloud SQL) with session logs (Cloud Bigtable) in a single SQL query, avoiding the need for a separate data warehouse or data movement.
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.
- ✓
Use BigQuery federated queries with external tables for both Cloud SQL and Bigtable
Why this is correct
Federated queries allow querying Cloud SQL and Bigtable in-place, no data movement.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Use Dataflow to continuously stream both Cloud SQL and Bigtable data into a single BigQuery dataset
Why it's wrong here
This moves data into BigQuery, not desired.
- ✗
Use Cloud Spanner as a unified database for both transactional and session data
Why it's wrong here
Migrating to Spanner is a larger change and not required; does not avoid data movement.
- ✗
Use Datastream to replicate Cloud SQL data to BigQuery, then join with Bigtable data using BigQuery's Bigtable external table
Why it's wrong here
This moves data to BigQuery, violating the 'avoid moving data' requirement.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the distinction between 'avoid moving data' and 'acceptable data replication' — candidates may incorrectly choose options that involve streaming or replication (like B or D) because they seem efficient, but the question explicitly prohibits moving data into a separate data warehouse.
Detailed technical explanation
How to think about this question
BigQuery federated queries use the BigQuery Storage API to read data directly from Cloud SQL (via JDBC) and Cloud Bigtable (via the Bigtable connector), executing the join in BigQuery's compute layer. This approach leverages BigQuery's serverless architecture for ad-hoc analytics but can incur higher latency and cost for large scans compared to native BigQuery tables. A real-world scenario is a retail platform that needs to correlate real-time clickstream data in Bigtable with inventory and order status in Cloud SQL for fraud detection, without duplicating data.
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 cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
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.
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FAQ
Questions learners often ask
What does this PCD question test?
Manage a Solution that Can Span Multiple Database Systems — This question tests Manage a Solution that Can Span Multiple Database Systems — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use BigQuery federated queries with external tables for both Cloud SQL and Bigtable — BigQuery federated queries allow you to query data in Cloud SQL and Cloud Bigtable directly using external tables, without moving the data. This approach meets the real-time analytics requirement by joining order data (Cloud SQL) with session logs (Cloud Bigtable) in a single SQL query, avoiding the need for a separate data warehouse or data movement.
What should I do if I get this PCD 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.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Last reviewed: Jul 4, 2026
This PCD 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 PCD exam.
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