PCDE Practice Test 5 — 10 Questions

Question 1

An organization uses Terraform with a GCS backend for state. They want to implement a GitOps workflow where changes merged to the main branch are automatically applied. The CI/CD pipeline uses a service account with Workload Identity Federation. Which THREE components are required? (Choose three.)

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

A service account with permissions to modify resources in the target projects.. Option C is correct because the pipeline's service account must hold IAM roles (e.g., roles/editor or specific resource-level roles) on the target projects so that Terraform apply can create, modify, and delete the managed resources. Option D is correct because a GitOps workflow requires a Git repository holding the Terraform configurations; merges to main are the trigger and the repo is the source of truth for desired state. Option E is correct because an automated CI/CD system such as Cloud Build is needed to run terraform init, plan, and apply on merge to main, using Workload Identity Federation to impersonate the service account without long-lived keys. Option A is not required: while GCS object versioning is a recommended safeguard for state recovery, it is not a mandatory component for the GitOps apply workflow itself. Option B is not required: Terraform Cloud is an alternative execution platform and is unnecessary when the pipeline runs Terraform directly against a GCS backend.

Answer

A Cloud Storage bucket with object versioning enabled for Terraform state.

Answer

A Terraform Cloud workspace configured with the same GCS backend.

Question 2

You are using Cloud Spanner and need to add a new column to an existing table. The table has millions of rows and must remain fully available for reads and writes during the schema change. What is the correct approach?

Accepted Answer

Use gcloud spanner databases ddl update with the ALTER TABLE statement; Spanner applies the change online.. Cloud Spanner supports online schema changes using DDL statements executed via `gcloud spanner databases ddl update`. The ALTER TABLE statement adds the column without locking the table or requiring downtime; Spanner applies the change in the background while the table remains fully available for reads and writes. This is the standard, supported method for schema modifications in Spanner.

Answer

Export the table using Dataflow, add the column locally, then import the data back.

Answer

Use gcloud spanner instances update to modify the table schema.

Answer

Take the instance offline, run the ALTER TABLE, then bring it back online.

Question 3

A company is designing a star schema for a BI dashboard that tracks sales performance. The dashboard needs to aggregate sales by product, store, and date. Which schema design is most appropriate?

Accepted Answer

Create a fact table with foreign keys to dimension tables for product, store, and date. A star schema is the standard dimensional model for BI dashboards: a central fact table (sales measures) joined via foreign keys to denormalized dimension tables (product, store, date). This keeps joins simple and shallow, which lets the query engine scan and aggregate quickly for slice-and-dice reporting. Option C matches that pattern exactly, with each dimension represented by its own table referenced from the fact table.

Answer

Store all data in a single table using nested JSON arrays for product and store details

Answer

Create a single wide table with all attributes (product, store, date, sales)

Answer

Use a fully normalized snowflake schema with separate tables for each level of hierarchy

Question 4

A data analyst runs a query joining several large tables and gets 'Resources exceeded' error. They need to reduce memory usage without changing the query logic. What should they do?

Accepted Answer

Use a subquery to pre-aggregate the largest table before joining. Pre-aggregating the largest table in a subquery reduces the amount of data that needs to be shuffled and joined in memory. In BigQuery, this minimizes the bytes processed and the memory footprint of the join operation, directly addressing the 'Resources exceeded' error without altering the overall query logic.

Answer

Use APPROX_COUNT_DISTINCT for counting distinct values

Answer

Increase the slot reservation

Answer

Use SELECT * in the subquery to ensure all columns are available

Question 5

A company uses Cloud Build to build a multi-module Maven project. They want to run unit tests for module A and integration tests for module B in parallel. In cloudbuild.yaml, how should they configure the steps to run in parallel?

Accepted Answer

steps:
- id: 'unit'
  waitFor: ['-']
  ...
- id: 'integration'
  waitFor: ['-']
  .... In Cloud Build, setting `waitFor: ['-']` on a step makes it start immediately without waiting for any other step, effectively allowing both the 'unit' and 'integration' steps to run in parallel. This configuration meets the requirement to run unit tests for module A and integration tests for module B concurrently.

Answer

steps:
- id: 'unit'
  ...
- id: 'integration'
  waitFor: ['-']
  ...

Answer

steps:
- id: 'unit'
  waitFor: ['previous']
  ...
- id: 'integration'
  waitFor: ['unit']
  ...

Answer

Steps run sequentially by default; parallelism is not supported.

Question 6

A developer wants to deploy a containerized application to Cloud Run with a requirement that the service has at least 2 instances always running to handle low-latency requests. Which flag should they use with gcloud run deploy?

Accepted Answer

--min-instances=2. The `--min-instances` flag in `gcloud run deploy` specifies the minimum number of container instances that must remain warm and ready to serve requests at all times. Setting `--min-instances=2` ensures Cloud Run keeps at least two instances always running, which eliminates cold starts and guarantees low-latency responses for incoming traffic.

Answer

--concurrency=2

Answer

--cpu-throttling

Answer

--max-instances=2

Question 7

Match each database migration term to its description.

Accepted Answer

Homogeneous migration: Migrating a database from one source engine to the same target engine.. The correct matches are: Homogeneous migration = same engine, Heterogeneous migration = different engine, Database Migration Service = Google Cloud's database migration tool. Common confusions involve swapping the definitions of homogeneous and heterogeneous, or misattributing DMS to application migration.

Answer

Homogeneous migration: Migrating a database to a different database engine.

Answer

Heterogeneous migration: Migrating a database to the same database engine.

Answer

Database Migration Service (DMS): A tool for migrating applications to compute engines.

Question 8

A Cloud Spanner database needs a new index added to support a new query pattern. The database is serving live traffic. Which approach should be taken?

Accepted Answer

Create the index using DDL statement 'CREATE INDEX' — it will be applied online without downtime.. Cloud Spanner supports online schema changes, including index creation, without downtime. The 'CREATE INDEX' DDL statement is applied asynchronously in the background, allowing the database to continue serving live traffic while the index is built. This is the correct approach because it avoids any interruption to the application.

Answer

Export the data, create a new database with the index, and import the data.

Answer

Stop the application, add the index, and restart.

Answer

Use gcloud spanner databases add-index command.

Question 9

A data engineer is designing a BigQuery schema for a dataset that will be used for both ad-hoc analysis and scheduled dashboards. They want to optimize costs and performance. Which three strategies should they consider? (Choose three.)

Accepted Answer

Use partitioning on a date column for time-based queries.. Partitioning on a date column (Option C) is correct because BigQuery uses the date column to prune partitions during query execution, significantly reducing the amount of data scanned and thus lowering costs and improving performance for time-based queries. This is a core optimization for both ad-hoc analysis and scheduled dashboards that frequently filter by date ranges.

Answer

Use wildcard tables with a suffix filter.

Answer

Store data in multiple tables per day.

Question 10

Which TWO actions are required to set up point-in-time recovery (PITR) for Cloud SQL for MySQL? (Choose 2)

Accepted Answer

Enable binary logging.

Answer

Set the 'log_bin' flag to ON in the database flags.

Answer

Create a read replica in a different region.

Answer

Configure a cross-region backup replica.