- A
Dataflow with JDBC source
Why wrong: Dataflow can read from JDBC but it's not optimized for continuous CDC; Datastream is better.
- B
Pub/Sub with a Cloud Function that writes to BigQuery
Why wrong: This would require setting up a custom CDC mechanism; Datastream is purpose-built.
- C
Storage Transfer Service
Why wrong: Storage Transfer Service transfers files, not database changes.
- D
Datastream
Datastream is the managed CDC service that can stream changes from PostgreSQL to BigQuery with minimal latency.
Question 209 of 1,000
PDE Ingesting and Processing the Data Practice Question
This PDE practice question tests your understanding of ingesting and processing the data. 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.
You are migrating an on-premises PostgreSQL database to Cloud SQL. You need to continuously replicate changes to BigQuery for real-time analytics with minimal latency. Which service should you use?
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
✓
Datastream
Datastream is designed for change data capture (CDC) from databases like PostgreSQL, MySQL, and Oracle to BigQuery or GCS. It provides low-latency replication. Pub/Sub and Dataflow are not directly for CDC. Storage Transfer Service is for file transfers, not database replication.
Key principle: ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Dataflow with JDBC source
Why it's wrong here
Dataflow can read from JDBC but it's not optimized for continuous CDC; Datastream is better.
- ✗
Pub/Sub with a Cloud Function that writes to BigQuery
Why it's wrong here
This would require setting up a custom CDC mechanism; Datastream is purpose-built.
- ✗
Storage Transfer Service
Why it's wrong here
Storage Transfer Service transfers files, not database changes.
- ✓
Datastream
Why this is correct
Datastream is the managed CDC service that can stream changes from PostgreSQL to BigQuery with minimal latency.
Related concept
Standard ACLs match source addresses.
Common exam traps
Common exam trap: ACLs stop at the first match
ACLs are processed top to bottom. The first matching entry wins, and an implicit deny usually exists at the end.
Detailed technical explanation
How to think about this question
ACL questions test precision: source, destination, protocol, port and direction. A generally correct ACL can still fail if it is applied on the wrong interface or in the wrong direction.
KKey Concepts to Remember
- Standard ACLs match source addresses.
- Extended ACLs can match source, destination, protocol and ports.
- The first matching ACL entry is used.
- There is usually an implicit deny at the end.
TExam Day Tips
- Check inbound versus outbound direction.
- Read the ACL from top to bottom.
- Look for a broader permit or deny above the intended line.
Key takeaway
ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
Real-world example
How this comes up in practice
A media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
What to study next
Got this wrong? Here's your next step.
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related PDE ACL questions on filtering logic and placement.
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Ingesting and Processing the Data — study guide chapter
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FAQ
Questions learners often ask
What does this PDE question test?
Ingesting and Processing the Data — This question tests Ingesting and Processing the Data — Standard ACLs match source addresses..
What is the correct answer to this question?
The correct answer is: Datastream — Datastream is designed for change data capture (CDC) from databases like PostgreSQL, MySQL, and Oracle to BigQuery or GCS. It provides low-latency replication. Pub/Sub and Dataflow are not directly for CDC. Storage Transfer Service is for file transfers, not database replication.
What should I do if I get this PDE question wrong?
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related PDE ACL questions on filtering logic and placement.
What is the key concept behind this question?
Standard ACLs match source addresses.
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Last reviewed: Jul 4, 2026
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.
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