PCD Practice Test 43 — 15 Questions

Question 1

An organization uses Flyway for versioned schema migrations. They are migrating from PostgreSQL to Cloud SQL for PostgreSQL. What is the best practice for applying schema changes during the migration?

Accepted Answer

Use Flyway migration scripts in a CI/CD pipeline. Flyway integrates well with Cloud SQL and CI/CD. The best practice is to use Flyway migrations to apply schema changes before or after data migration, ensuring version control and repeatability.

Answer

Use Database Migration Service to apply schema changes

Answer

Manually apply schema changes using pgAdmin

Answer

Use Cloud SQL import wizard

Question 2

A developer is building a CI/CD pipeline for a microservices application. The pipeline should build a container image, run unit tests, and deploy to Google Kubernetes Engine (GKE) only if all tests pass. Which Google Cloud service is best suited for orchestrating this pipeline?

Accepted Answer

Cloud Build. Cloud Build is the correct choice because it is a fully managed CI/CD platform that natively supports building container images, running unit tests, and deploying to GKE. It can be configured with a cloudbuild.yaml file to define steps for building, testing, and deploying, and it only proceeds to the deploy step if all prior steps (including tests) succeed. This makes it the best fit for orchestrating the entire pipeline in a single, integrated service.

Answer

Compute Engine

Answer

Cloud Run

Answer

Cloud Functions

Question 3

An organization is migrating an on-premises PostgreSQL database to Cloud SQL. They need minimal downtime and want to use Database Migration Service (DMS) with continuous change data capture (CDC). What is the correct sequence of steps?

Accepted Answer

Create connection profile → start migration job with full dump → CDC phase → promote replica. Database Migration Service for PostgreSQL follows a defined lifecycle: create the connection profile (source and destination credentials/connectivity), start the migration job which performs the initial full dump, then transition into the continuous CDC phase where ongoing changes are replicated, and finally promote the destination Cloud SQL replica to primary during cutover. This sequence ensures data consistency and minimal downtime because CDC keeps the target in sync until the moment of promotion.

Answer

Create connection profile → start full dump → promote to primary

Answer

Start CDC directly without full dump → promote replica

Answer

Promote replica immediately after creating connection profile

Question 4

Which TWO Google Cloud services can be used to build a data pipeline that transforms and moves data between different databases? (Select 2)

Accepted Answer

Dataflow. Dataflow (A) is correct because it is a fully managed Apache Beam service that can build both batch and streaming pipelines to transform data and move it between sources and sinks, including different databases via built-in I/O connectors. Dataproc (C) is correct because it is a managed Spark/Hadoop service whose jobs (Spark, Hive, Pig) can read from one database, transform the data, and write to another, making it suitable for ETL/ELT pipelines. Cloud Scheduler (B) is only a cron-based job trigger and cannot itself transform or move data. Memorystore (D) is an in-memory cache (Redis/Memcached) for low-latency access, not a data pipeline or transformation engine. Cloud SQL Proxy (E) only provides secure connectivity to Cloud SQL instances and performs no data transformation or movement between databases.

Answer

Cloud Scheduler

Answer

Memorystore

Answer

Cloud SQL Proxy

Question 5

An organization is planning a re-architect migration of a monolithic Oracle database to a microservices architecture using Cloud SQL for PostgreSQL and Cloud Spanner. They need to split the schema into multiple databases while maintaining data consistency across services. Which approach should they use?

Accepted Answer

Use Cloud SQL for PostgreSQL for each service and implement sagas to handle distributed transactions.. For microservices, each service should own its database. To maintain consistency across services, they should implement compensating transactions (sagas) rather than distributed transactions. Cloud Spanner can be used if strong consistency is required across global scales, but for microservices, the pattern is to use eventual consistency with sagas.

Answer

Use a single Cloud SQL for PostgreSQL instance with different schemas per service.

Answer

Use BigQuery to store all data and query across services.

Answer

Use Cloud Spanner for all services to maintain ACID transactions across databases.

Question 6

A financial services company is migrating a critical PostgreSQL database to AlloyDB using Database Migration Service (DMS). They want to minimize downtime by using continuous change data capture (CDC). After the initial full dump, what phase must be completed before promoting the replica to primary?

Accepted Answer

Complete the CDC phase. DMS provides a CDC phase that continuously replicates changes from the source to the destination. Only after the replica catches up and the application can be stopped can you promote the replica. The full dump is the first step, then CDC ensures consistency.

Answer

Perform a final manual sync

Answer

Take a new full dump

Answer

Delete all existing data in AlloyDB

Question 7

A company needs a database for an e-commerce application that requires strong consistency and the ability to scale horizontally across multiple regions. They expect high write throughput and need to support SQL queries. Which database should they choose?

Accepted Answer

Cloud Spanner. Cloud Spanner is a globally distributed, strongly consistent relational database that scales horizontally and supports SQL. Bigtable is NoSQL and eventually consistent. Cloud SQL is regional and does not scale horizontally. Firestore is NoSQL and eventually consistent across regions.

Answer

Cloud Bigtable

Answer

Cloud SQL

Answer

Firestore

Question 8

A company is migrating an on-premises PostgreSQL database to Cloud SQL for PostgreSQL. They require automatic failover within 60 seconds in case of a zonal failure. The database must be available in the same region for low latency. Which configuration should they choose?

Accepted Answer

Create a Cloud SQL for PostgreSQL regional instance with HA configuration.. Cloud SQL HA configuration uses a regional instance with a standby in a different zone within the same region. Automatic failover occurs within 60 seconds. Zonal instances do not provide HA. Cross-region replicas are for disaster recovery, not automatic failover within the region.

Answer

Create a Cloud SQL for PostgreSQL zonal instance with one standby replica in the same zone.

Answer

Create a Cloud SQL for PostgreSQL instance with a local SSD and enable automatic storage increase.

Answer

Create a Cloud SQL for PostgreSQL zonal instance and add a cross-region read replica.

Question 9

A company uses Cloud Storage for backups. They need to comply with a regulation requiring immutable storage for 7 years. Which bucket configuration should they use?

Accepted Answer

Set a retention policy and lock the bucket. Locking a retention policy in Cloud Storage enforces immutable storage for the specified duration (7 years). Once locked, the retention policy cannot be removed or shortened, ensuring compliance with regulations that require data to be preserved in its original state and not modifiable or deletable until the retention period expires.

Answer

Use a bucket with a retention policy (not locked)

Answer

Set a lifecycle rule to archive to Coldline

Answer

Enable Object Versioning

Question 10

A team uses Cloud Source Repositories for version control and Cloud Build for CI. The build configuration file (cloudbuild.yaml) includes a step that runs unit tests. The team wants to ensure that the build fails if any test fails. What should the developer do?

Accepted Answer

Ensure the test command in the build step returns a non-zero exit code when tests fail.. Cloud Build executes each step as a container, and the build step's success or failure is determined by the exit code of the command run inside that container. If the test command (e.g., `npm test` or `pytest`) returns a non-zero exit code when tests fail, Cloud Build will automatically mark that step as failed and stop the build. No special configuration or custom builder is required beyond ensuring the test command itself propagates the failure exit code.

Answer

Use Cloud Build's built-in test runner that automatically fails the build on test failure.

Answer

Create a custom builder that runs tests and emits a non-zero exit code on failure.

Answer

Add a pre-build step that checks test results and triggers a build failure if needed.

Question 11

An organization wants to cache frequently accessed session data for a web application to reduce database load. They require sub-millisecond latency and support for pub/sub messaging. Which Google Cloud service should they use?

Accepted Answer

Memorystore for Redis. Memorystore for Redis is the correct choice because it provides an in-memory data store with sub-millisecond latency, ideal for caching frequently accessed session data. It also natively supports pub/sub messaging via Redis's built-in PUBLISH/SUBSCRIBE commands, meeting both requirements precisely.

Answer

Cloud SQL

Answer

Cloud Bigtable

Answer

Firestore

Question 12

A developer is writing unit tests for a Python application that will run on Cloud Functions. The function makes HTTP requests to an external API. The developer wants to avoid making actual network calls during tests. What should the developer use?

Accepted Answer

Mock the HTTP requests using a library like unittest.mock.. `unittest.mock` allows the developer to replace the actual HTTP request calls (e.g., `requests.get`) with mock objects that return controlled responses, preventing any real network traffic. This is essential for unit testing Cloud Functions where external API calls must be isolated to ensure tests are fast, deterministic, and do not depend on external services.

Answer

Use a test double to replace the entire function.

Answer

Use dependency injection to pass a fallback URL.

Answer

Deploy the function to Cloud Functions and run integration tests.

Question 13

A company wants to deploy a non-relational database for a real-time bidding application that requires low latency (under 10ms) and high throughput (millions of requests per second). The data model is key-value with a timestamp component. Which Google Cloud database is most appropriate?

Accepted Answer

Cloud Bigtable. Cloud Bigtable is designed for high-throughput, low-latency key-value workloads with time-series data, such as real-time bidding.

Answer

Cloud Spanner

Answer

Firestore

Answer

Cloud SQL

Question 14

A company is designing a global e-commerce application that needs low-latency access for users worldwide. The application serves static content (images, CSS) and dynamic API responses. Which Google Cloud service should they use to cache both types of content at the edge?

Accepted Answer

Cloud CDN. Cloud CDN is the correct choice because it uses Google's global edge cache to deliver both static content (e.g., images, CSS) and dynamic API responses (via cacheable dynamic content or cache-fill from origin). It integrates with HTTP(S) Load Balancing to cache responses at edge locations, reducing latency for users worldwide.

Answer

Cloud Armor

Answer

Cloud Storage

Answer

HTTP(S) Load Balancing

Question 15

A team is designing a globally distributed application on Google Cloud that requires strong consistency for writes but can tolerate eventual consistency for reads. The application expects millions of concurrent users. Which two strategies should they implement? (Choose two.)

Accepted Answer

Use Cloud Spanner for write operations requiring strong consistency.. Cloud Spanner provides strongly consistent writes globally through synchronous replication using the TrueTime API and Paxos-based consensus. This ensures that all write operations are immediately consistent across regions, meeting the requirement for strong consistency on writes.

Answer

Use Firestore in multi-region mode for all operations.

Answer

Deploy Cloud SQL with cross-region replication for read scalability.

Answer

Use Cloud Bigtable for reading data with strong consistency.