PCD Practice Test 7 — 10 Questions

Question 1

A developer wants to run a single test suite across multiple environments (dev, staging, prod) using Cloud Build. What is the best practice?

Accepted Answer

Use a single Cloud Build trigger with substitutions to parameterize the environment.. Cloud Build triggers support substitutions (e.g., `$_ENV`) that allow a single trigger to parameterize the environment variable, enabling the same test suite to run across dev, staging, and prod without duplicating configuration. This aligns with Infrastructure as Code (IaC) principles and reduces maintenance overhead.

Answer

Use Cloud Deploy to run tests in each environment.

Answer

Use separate branches for each environment.

Answer

Create separate Cloud Build triggers for each environment.

Question 2

An organization runs a stateful application on GKE that uses PersistentVolumes. They want to perform a rolling update of the application without disrupting the underlying persistent data. What should they use?

Accepted Answer

A StatefulSet with a PersistentVolumeClaim template.. A StatefulSet is the correct choice because it is designed for stateful applications that require stable, unique network identifiers and persistent storage. By including a PersistentVolumeClaim template in the StatefulSet spec, each Pod gets its own dedicated PersistentVolume that persists across rescheduling and rolling updates, ensuring data is not disrupted.

Answer

A ReplicaSet with a headless service.

Answer

A DaemonSet with a PodDisruptionBudget.

Answer

A Deployment with a PersistentVolumeClaim template.

Question 3

A company is designing a polyglot persistence architecture. They need to use Cloud SQL for transactions, Bigtable for real-time analytics, and BigQuery for reporting. They also need to keep data across these systems eventually consistent. Which TWO approaches should they use?

Accepted Answer

Implement a saga pattern with compensating transactions for each write.

Answer

Use two-phase commit across all databases.

Answer

Use Cloud Spanner as a single database to avoid polyglot complexity.

Answer

Write to all three databases in a single transaction using distributed transactions.

Question 4

You are designing a Cloud Bigtable schema for a time-series application. To optimize performance and avoid hot spots, which THREE row key design practices should you follow? (Choose 3)

Accepted Answer

Place the highest cardinality field (e.g., device ID) first in the row key. Reversing timestamps, salting keys, and promoting high-cardinality fields to the start of the row key are recommended to distribute writes evenly.

Answer

Use a single table for all data

Answer

Use sequential integers as row keys

Question 5

You need to migrate an on-premises MySQL 5.7 database (2 TB) to Cloud SQL for MySQL with minimal downtime. Database Migration Service (DMS) is chosen. What is the correct sequence of steps to ensure a successful continuous migration?

Accepted Answer

Set up a connection profile for the source, create a DMS migration job (full dump + CDC), monitor the initial dump, then promote the replica to complete migration.. DMS continuous migration first performs a full dump (initial snapshot), then switches to CDC to replicate ongoing changes. After the initial dump, you validate the replica and promote it to make it the primary. The correct order: create connection profile for source, create migration job with full dump + CDC, monitor initial dump, then promote when ready.

Answer

Use mysqldump to export the database, import to Cloud SQL, then set up DMS for CDC only.

Answer

Create a DMS continuous migration job directly without a connection profile.

Answer

First promote the Cloud SQL replica, then create the connection profile.

Question 6

An online gaming platform uses Cloud Spanner as its globally distributed database. They notice that write latency increases significantly during peak hours. The application performs many single-row writes with high consistency requirements. Which design change would most effectively reduce write latency?

Accepted Answer

Use interleaved tables to colocate related rows.. Interleaved tables in Cloud Spanner physically colocate parent and child rows, reducing the number of splits and cross-node round trips for related single-row writes. This minimizes distributed transaction overhead and write latency, especially under high consistency requirements, without requiring additional nodes or sacrificing consistency.

Answer

Increase the number of nodes in the Spanner instance.

Answer

Switch to eventual consistency mode for writes.

Answer

Split the table into multiple smaller tables.

Question 7

Match each Google Cloud service to its primary purpose.

Accepted Answer

Cloud Run: A fully managed compute platform for containerized applications.. Cloud Run deploys containers, Cloud Functions runs event-driven functions, and Cloud Storage stores unstructured objects. Common confusions include swapping the definitions of Cloud Run and Cloud Functions, or mistaking Cloud Storage for a database service like Cloud SQL.

Answer

Cloud Run: A serverless execution environment for building and connecting cloud services.

Answer

Cloud Storage: A fully managed relational database for MySQL, PostgreSQL, and SQL Server.

Question 8

A team uses Cloud Build to build and deploy a Node.js application to App Engine flexible environment. The build succeeds, but the deployment fails with 'ERROR: (gcloud.app.deploy) Error Response: [9] Application startup error!' The team checks logs and sees 'Error: Module not found: 'express''. What is the most likely cause?

Accepted Answer

The dependencies are not installed during the build step before deploying.. The error 'Module not found: express' indicates that the Node.js dependencies (specifically the 'express' package) are not present in the deployed application. In Cloud Build, the build steps must explicitly install dependencies (e.g., via 'npm install') before the deploy step. If the build configuration does not include an 'npm install' step, the dependencies listed in package.json are not copied to the App Engine flexible environment, causing the startup error.

Answer

The build step includes 'npm test' which fails.

Answer

The Node.js version specified in app.yaml is incompatible with the dependencies.

Answer

The app.yaml file is missing from the root of the repository.

Question 9

You are migrating an on-premises Oracle database to Cloud SQL for PostgreSQL. You need to assess the migration feasibility and convert the schema. Which tools should you use?

Accepted Answer

Use Ora2Pg for schema conversion and DMS for data migration.. Ora2Pg is an open-source tool that converts Oracle schema to PostgreSQL. Database Migration Service (DMS) supports migration from Oracle to Cloud SQL for PostgreSQL. For assessment, you can use tools like Oracle Migration Toolkit or Ora2Pg's assessment mode.

Answer

Use mysqldump to export and import to PostgreSQL.

Answer

Use pg_dump to export the Oracle database and import into Cloud SQL.

Answer

Use DMS directly with Oracle source; it automatically converts schema.

Question 10

A mobile app developer wants to store user preferences and provide offline sync capabilities. The database should be serverless and automatically scale with usage. Which Google Cloud database is best suited?

Accepted Answer

Cloud Firestore. Cloud Firestore is a serverless, NoSQL document database that automatically scales with usage, making it ideal for storing user preferences and providing offline sync capabilities via its built-in offline data persistence and real-time synchronization. It supports mobile and web clients with automatic multi-region replication and strong consistency, aligning perfectly with the requirements of a mobile app developer.

Answer

Cloud Spanner

Answer

Cloud SQL

Answer

Cloud Bigtable