PCDE Practice Test 39 — 15 Questions

Question 1

Which two of the following are best practices when designing BigQuery schemas? (Choose two.)

Accepted Answer

Use denormalization to reduce the number of joins. Option B is correct because BigQuery is a columnar, distributed analytics engine where joins are expensive and require data shuffling across slots, so denormalizing (flattening) related data into wide tables minimizes joins and improves query performance. Option D is correct because using repeated fields (arrays) to embed parent-child relationships in a single table lets queries use UNNEST instead of joins, which is the recommended pattern for hierarchical data in BigQuery. Option A is not a schema design best practice but an access-control feature, option C is not inherently a best practice since RECORD should be used when nesting genuinely reduces joins or models structure, and option E is wrong because consolidating all data into one table harms performance, governance, and cost efficiency.

Answer

Use column-level security to restrict access

Answer

Use the type RECORD for structured data

Answer

Use a single table for all data to simplify queries

Question 2

An engineer needs to create a build trigger in Cloud Build that runs every day at midnight. Which type of trigger should they use?

Accepted Answer

Scheduled trigger. Cloud Build supports a dedicated trigger type called a 'scheduled trigger' (also called a cron trigger) that runs builds on a defined schedule using a cron expression. To run every day at midnight, the engineer configures a scheduled trigger with a cron expression such as '0 0 * * *'. This is the only trigger type designed for time-based execution rather than event-based execution.

Answer

Push to branch trigger

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Pull request trigger

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Manual trigger

Question 3

A DevOps engineer is bootstrapping a new Google Cloud organization. They need to enforce that all Compute Engine VM instances must use Shielded VM features. Which method should they use?

Accepted Answer

Apply an organization policy with constraint constraints/compute.requireShieldedVm at the organization level.. Organization policies are the centralized, hierarchical mechanism in Google Cloud for enforcing constraints across all projects in an organization, folder, or project. The constraint constraints/compute.requireShieldedVm enforces that Compute Engine VMs must have Shielded VM features (Secure Boot, vTPM, Integrity Monitoring) enabled, and applying it at the organization level makes it apply to every project beneath. This is the correct, scalable enforcement method.

Answer

Create a custom IAM role that grants compute.instances.create permission only for Shielded VM projects.

Answer

Use Deployment Manager templates that include Shielded VM initialization config.

Answer

Enable Shielded VM as a default in the Compute Engine service quota settings.

Question 4

An SRE team wants to ensure that no single person can deploy to production without a peer review. Which Google Cloud service or feature should they use?

Accepted Answer

Cloud Build with a trigger that runs only on merges to main branch that have passed pull request approval in Cloud Source Repositories. Cloud Build with a trigger that only runs on merges to main that have passed pull request approval in Cloud Source Repositories enforces a peer-review gate before deployment, because the build (and thus the deploy) cannot execute until the PR is approved and merged. This satisfies the requirement that no single person can deploy without peer review. The approval happens in the source repository, and the trigger enforces it as a precondition.

Answer

Cloud Audit Logs to monitor who deploys

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Cloud Scheduler to run deployments at fixed times

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IAM roles to restrict deployment to a single user

Question 5

A DevOps engineer wants to trigger a Cloud Build pipeline automatically every time a pull request is created against the main branch of a Cloud Source Repositories repository. Which type of build trigger should they configure?

Accepted Answer

Pull request trigger. A pull request trigger in Cloud Build is specifically designed to run builds when a pull request is created or updated against a target branch. This allows automated checks like tests, linting, or security scans to run before code is merged. Configuring a PR trigger against the main branch satisfies the requirement exactly.

Answer

Push trigger

Answer

Manual trigger

Answer

Scheduled trigger

Question 6

A developer wants to use Cloud Build to deploy a container to Cloud Run. They have written a cloudbuild.yaml file with a step that runs gcloud run deploy. The build fails with a permission error. What is the most likely cause?

Accepted Answer

The Cloud Build service account does not have the Cloud Run Admin role. When Cloud Build runs a build, it executes steps using the Cloud Build service account (by default the legacy Cloud Build SA or a user-specified SA). If that service account lacks the Cloud Run Admin role (roles/run.admin), the 'gcloud run deploy' step fails with a permission error even though the command syntax is correct. Granting the Cloud Build service account the necessary Cloud Run roles resolves the failure.

Answer

The gcloud command is incorrect

Answer

The Cloud Build trigger is misconfigured

Answer

The Cloud Run API is not enabled in the project

Question 7

An engineer is planning a migration from on-premises MySQL to Cloud SQL. They want to use Database Migration Service with continuous replication. What must be enabled on the source MySQL database before starting the migration job?

Accepted Answer

Binary logging. Database Migration Service with continuous replication requires binary logging (binlog) on the source MySQL instance to capture and stream ongoing changes. Binary logs record all data modifications (INSERT, UPDATE, DELETE) in a format that Cloud SQL can replay, enabling near-real-time replication without downtime. Without binary logging enabled, only a one-time snapshot migration is possible, not continuous replication.

Answer

Error log

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Slow query log

Answer

General query log

Question 8

A Cloud SQL for PostgreSQL instance is experiencing a surge in read traffic. The team wants to offload read queries without affecting write latency. What should they do?

Accepted Answer

Create a same-region read replica. A same-region read replica in Cloud SQL for PostgreSQL asynchronously replicates from the primary and serves read-only queries, offloading read traffic without touching the primary's write path. Same-region placement minimizes replication lag and network latency, which is critical when read replicas must stay closely consistent with the primary for application queries. This directly addresses the surge in read traffic while preserving write latency on the primary.

Answer

Enable automated backups

Answer

Create a cross-region read replica

Answer

Increase the CPU of the primary instance

Question 9

A service has an SLO of 99.9% availability over a 30-day window. The team wants to automate a deployment rollback if the error budget burn rate exceeds 10x over a 30-minute window. Which combination of Cloud Monitoring and Cloud Build should be used?

Accepted Answer

Create a custom burn rate alert in Cloud Monitoring that sends a notification to a Cloud Function via HTTP, which then triggers Cloud Build to rollback. The correct pattern is to create a burn rate alert in Cloud Monitoring based on the SLO's error budget, route the alert notification to a Cloud Function (or Pub/Sub topic) via a notification channel, and have that function trigger Cloud Build to perform the rollback. This uses Cloud Monitoring's native SLO burn rate alerting (which supports multi-window, multi-burn-rate alerts) and Cloud Build's API/trigger mechanism for the automated remediation.

Answer

Create a Cloud Scheduler job that checks Cloud Monitoring metrics every 30 minutes and triggers rollback if needed

Answer

Configure Cloud Build to poll Cloud Monitoring metrics and trigger rollback when burn rate exceeds threshold

Answer

Use Cloud Monitoring's built-in rollback action in alert policies

Question 10

Which Google Cloud service provides continuous, low-overhead profiling of CPU and memory usage to identify performance bottlenecks in production?

Accepted Answer

Cloud Profiler. Cloud Profiler is Google Cloud's continuous profiling service that collects CPU and heap allocation data from production applications with very low overhead (typically under 1% CPU). It aggregates stack traces over time to show which functions consume the most CPU or memory, making it the correct tool for identifying performance bottlenecks. Unlike monitoring or tracing, its purpose is specifically statistical, always-on profiling of running code.

Answer

Error Reporting

Answer

Cloud Monitoring

Answer

Cloud Trace

Question 11

Which Google Cloud service can be used to automate repetitive operational tasks such as restarting a VM or clearing a cache, as part of toil reduction?

Accepted Answer

Cloud Functions. Cloud Functions is a serverless, event-driven compute service that executes small pieces of code in response to triggers such as Pub/Sub messages, HTTP requests, or Cloud Scheduler events. It is the natural fit for automating small, repetitive operational tasks like restarting a VM or clearing a cache because it requires no server management and scales automatically. This directly supports toil reduction by replacing manual runbook steps with automated functions.

Answer

Compute Engine

Answer

Cloud Run

Answer

Cloud Build

Question 12

A DevOps engineer needs to set up billing export to analyze costs by team and environment. They have organized projects with labels: team (e.g., 'platform', 'data') and environment (e.g., 'prod', 'dev'). Which billing export configuration should they use?

Accepted Answer

Set up BigQuery billing export in the billing account. The export includes labels, enabling cost analysis by team and environment.. BigQuery billing export automatically includes resource labels in the exported tables, allowing direct SQL-based cost analysis by team and environment without custom scripting. This is the native, scalable, and recommended approach for multi-dimensional cost breakdowns in Google Cloud.

Answer

Use the Cloud Billing API to stream costs and store them in Firestore.

Answer

Export billing data to a Cloud Storage bucket and use a custom script to parse labels.

Answer

Configure budgets and alerts for each label combination.

Question 13

A company uses BigQuery for BI. They need to create a table that stores daily sales data with millions of rows. The query pattern is to aggregate sales by month for specific product categories. Which table design is most cost-effective and performant?

Accepted Answer

Partitioned table by date with clustering on product_category. Partitioning by date allows BigQuery to prune entire partitions when querying monthly aggregates, drastically reducing the data scanned. Clustering on product_category further organizes data within each partition, enabling efficient block-level pruning for category filters. This combination minimizes both cost (bytes billed) and query latency for the described workload.

Answer

Non-partitioned table with clustering on product_category

Answer

Non-partitioned, non-clustered table with manual sharding by date

Answer

Partitioned table by product_category with clustering on date

Question 14

A team is migrating an on-premises Oracle database to Cloud SQL for PostgreSQL using DMS. They have completed the schema conversion using Ora2Pg and are now setting up continuous migration. The source database is behind a firewall. Which connectivity method should they use for the source connection profile if they cannot use public IP?

Accepted Answer

Configure a VPN or Dedicated Interconnect with VPC. Since the source Oracle database is behind a firewall and cannot use a public IP, a VPN or Dedicated Interconnect with VPC provides a private, encrypted connection between the on-premises network and Google Cloud. This allows Database Migration Service (DMS) to reach the source database securely without exposing it to the public internet. DMS supports connectivity via these private network paths when public IP is not an option.

Answer

VPC peering

Answer

Cloud SQL Auth Proxy

Answer

IP allowlisting

Question 15

An SRE team wants to reduce toil associated with manual database schema migrations. They currently run SQL scripts manually during maintenance windows. Which Google Cloud service is most appropriate to automate this process in a repeatable way?

Accepted Answer

Cloud Build. Cloud Build is the correct choice because it is Google Cloud's managed CI/CD service that executes build steps defined in a declarative YAML or JSON config (cloudbuild.yaml), making it ideal for running repeatable, version-controlled database schema migration scripts as part of a pipeline. Migration SQL can be stored in source control and triggered automatically via Cloud Build triggers on commits or releases, eliminating manual maintenance-window execution and reducing toil. This aligns with the SRE principle of automating repetitive operational work through codified, auditable pipelines.

Answer

Cloud Scheduler

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Workflows

Answer

Cloud Functions