PCDE Multiple Select — 30 Questions

Question 1

A company is designing a database solution for a global social media application that requires strong consistency, high write throughput, and complex relational queries. Which TWO Google Cloud databases should they consider? (Choose 2)

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

Accepted Answer

Cloud Spanner. Cloud Spanner provides global strong consistency and relational support. AlloyDB offers strong consistency and high performance for relational workloads. Bigtable is eventually consistent. BigQuery is analytical. Firestore is not globally consistent.

Answer

Cloud Bigtable

Answer

BigQuery

Answer

Firestore

Question 2

Which TWO statements about Cloud Spanner schema changes are correct? (Choose 2)

Accepted Answer

Schema changes are applied asynchronously and may take minutes to hours to complete.

Answer

Schema changes require the instance to be restarted.

Answer

You can only add columns, not drop them.

Answer

Creating a secondary index requires taking the table offline.

Question 3

An engineer is migrating a 20 TB PostgreSQL database to AlloyDB using DMS continuous migration. The full dump phase is taking longer than expected. Which THREE factors could affect the duration of the full dump phase? (Choose THREE.)

Accepted Answer

The number of tables and indexes on the source.. Full dump time depends on data volume, network bandwidth, CPU/memory of the source, and configuration (e.g., parallel workers).

Answer

The version of the source PostgreSQL database.

Answer

The choice of SSL or non-SSL connection.

Question 4

An organization needs to design a disaster recovery plan for Cloud SQL for PostgreSQL with an RPO of 10 seconds and an RTO of 5 minutes. Which TWO solutions meet these requirements? (Choose 2)

Accepted Answer

Cloud SQL cross-region read replica with manual promotion.. Cloud SQL HA provides near-zero RPO and RTO under 60 seconds within the same region. Cross-region read replicas can achieve RPO of seconds if replication lag is low, and manual promotion takes minutes.

Answer

Export the database to Cloud Storage and import in another region.

Answer

Cloud SQL point-in-time recovery from backups.

Answer

Use Cloud SQL automated backups with cross-region copy.

Question 5

A company is migrating their on-premises MySQL database to Cloud SQL. The database is 500 GB and they have a 1 Gbps network connection. They want to minimize downtime. Which THREE steps should they take?

Accepted Answer

Perform a test migration to validate the process.. Performing a test migration validates the entire process, including schema compatibility, data integrity, and application connectivity, before the actual cutover. This reduces the risk of unexpected failures during the production migration, which is critical for minimizing downtime. A test migration also helps estimate the time required for the final cutover and allows for tuning of the Database Migration Service settings.

Answer

Export the database to a SQL file and import after the cutover.

Answer

Schedule a maintenance window for the cutover.

Question 6

A financial services company is designing a Cloud Spanner schema for a trading system. They have two main entities: 'accounts' and 'transactions'. Each account has many transactions, and queries almost always retrieve transactions for a specific account. Which TWO schema design strategies should they employ?

Accepted Answer

Ensure the primary key of transactions includes the account_id as the first part.. Cloud Spanner distributes rows across splits based on the primary key prefix. By making `account_id` the first part of the transactions table primary key, all transactions for a given account are co-located, enabling efficient range scans and point lookups without cross-node shuffling.

Answer

Use a secondary index on transactions.account_id.

Answer

Define a foreign key constraint from transactions to accounts.

Answer

Store transactions as a JSON array of repeating fields within the account record.

Question 7

A startup is using Firestore in Native mode for a real-time chat application. They want to design the schema for chat rooms and messages. Which TWO design patterns are recommended? (Choose two.)

Accepted Answer

Use a composite index on chat room ID and timestamp.. A composite index on chat room ID and timestamp is essential for efficiently querying messages in order within a specific chat room. Firestore requires composite indexes for queries that combine equality filters on one field (chat room ID) with an order on another (timestamp). Option E is correct because storing messages as documents in a subcollection under each chat room document is the recommended pattern for Firestore, as it allows scalable, independent message collections per room without hitting the 1 MiB document size limit.

Answer

Use arrays in the chat room document to store message IDs.

Answer

Store all messages in a single top-level collection with a field for chat room ID.

Answer

Use a separate top-level collection for each chat room.

Question 8

A multinational corporation uses BigQuery to combine sales data from multiple regions. Each region stores data in separate tables with identical schemas. The BI team needs to create a unified view for a dashboard that queries data by region and product. Which TWO strategies should the data engineer implement to optimize query performance and reduce costs?

Accepted Answer

Partition the table by date and cluster by region and product. Partitioning the table by date and clustering by region and product enables partition pruning and clustering block elimination, reducing data scanned and costs. Option B is correct because wildcard tables with a filter on _TABLE_SUFFIX allow BigQuery to query only the required region tables, minimizing data read and cost. The other options are not optimal: C (UNION ALL view) does not reduce data scanned unless underlying tables are partitioned/clustered; D (materialized views for each region) adds complexity and cost; E (single table with region column) may still scan all data if not partitioned/clustered properly, and does not leverage region-specific tables.

Answer

Create a view with UNION ALL of all region tables

Answer

Create materialized views for each region

Answer

Store all data in a single table with region as a column

Question 9

A company is migrating a large Oracle database to Cloud Spanner. They need to define the schema for relational tables with foreign keys. Which THREE considerations are important when designing the Spanner schema? (Choose three.)

Accepted Answer

Use INTERLEAVE tables to model parent-child relationships.. Options B, D, and E are correct. Interleaved tables (B) model parent-child relationships and optimize joins and data locality. Secondary indexes (D) are essential for efficient queries on non-key columns. Cloud Spanner enforces foreign key constraints (E) to maintain referential integrity. Option A is incorrect because primary key columns cannot be NULL. Option C is incorrect because composite primary keys are commonly used in Spanner.

Answer

Use NULL values in primary key columns to allow optional fields.

Answer

Avoid using composite primary keys; use single-column keys instead.

Question 10

A company wants to reduce BigQuery query costs for their BI workloads. Which THREE actions effectively lower the amount of data processed per query? (Choose THREE.)

Accepted Answer

Use partitioned tables on date column. Partitioned tables in BigQuery allow queries to use the WHERE clause to filter on the partition column (e.g., a date column), so BigQuery can prune entire partitions from the scan. This directly reduces the amount of data read and billed, lowering query costs. Option A is correct because it is a primary cost-control mechanism in BigQuery.

Answer

Use LIMIT in subqueries to reduce output

Answer

Use SELECT * to avoid missing columns

Question 11

A company is using Bigtable for a high-throughput write workload. They need to monitor replication lag between clusters in a replicated setup and ensure that reads are eventually consistent. Which two configurations should they check? (Choose TWO.)

Accepted Answer

Ensure replication is set to asynchronous (default). Bigtable replication is asynchronous and eventually consistent by default. Replication lag can be monitored using the 'replication lag' metric in Cloud Monitoring. Consistency levels are not configurable; async is the default.

Answer

Create a replication dashboard in Data Studio

Answer

Set the replication consistency level to 'strong'

Answer

Enable synchronous replication for zero lag

Question 12

A team wants to implement an on-call rotation using Cloud Monitoring and third-party tools. Which three components are essential for setting up on-call alerting? (Choose THREE.)

Accepted Answer

An escalation policy. Essential components: alerting policy to trigger notifications, notification channel to reach on-call engineers, and escalation policy to handle unacknowledged alerts. A dashboard and runbook are helpful but not essential for the on-call rotation itself.

Answer

A Cloud Monitoring dashboard

Answer

A runbook for incident response

Question 13

During a cutover from MySQL to Cloud SQL, the team must minimize downtime. Which THREE steps are essential for a successful cutover with minimal data loss?

Accepted Answer

Verify that DMS replication lag is zero.. Quiesce writes to stop changes, verify replication lag is zero to ensure all changes are applied, then promote the destination to make it writable. Updating connection strings and testing are also needed but the three essential steps for data integrity are quiescing, verifying lag, and promoting.

Answer

Enable point-in-time recovery on the destination.

Answer

Take a full backup of the source after quiescing.

Question 14

A company wants to implement Binary Authorization for containers deployed to GKE. They need to ensure that only images signed by their internal CI system are allowed to run. Which three components are required?

Accepted Answer

An attestor in Binary Authorization. Binary Authorization requires images to be signed (e.g., using Cloud Key Management Service or Signify), an attestor that verifies signatures, and an admission controller (Binary Authorization) that enforces the policy on the cluster.

Answer

Cloud Build with privilege escalation mode

Answer

Container Registry with vulnerability scanning enabled

Question 15

A company is designing a disaster recovery strategy for their Cloud Spanner database. They need an RPO of less than 30 seconds and an RTO of less than 1 minute. Which two configurations would meet these requirements? (Choose TWO)

Accepted Answer

Multi-region configuration with read-write replicas (e.g., nam3). The correct answers are B and D. A multi-region configuration with read-write replicas (e.g., nam3) provides automatic failover across regions with an RPO of approximately 15 seconds and an RTO of less than 1 minute, meeting the requirements for region-level failures. A regional instance in Cloud Spanner provides synchronous replication within the region, achieving an RPO of zero and an RTO of seconds, which meets the requirements for zone-level failures within a region. Option A (cross-region backup and restore) typically has an RPO of hours and RTO of hours, so it does not meet the strict RPO/RTO. Option C (point-in-time recovery) provides RPO of seconds to minutes but depends on backups and may not achieve RTO <1 minute for restore operations. Option E (multi-region with read-only replicas) does not support automatic failover because read-only replicas cannot become the new leader, so failover is not automatic and RTO would be longer.

Answer

Cross-region backup and restore

Answer

Point-in-time recovery (PITR)

Answer

Multi-region configuration with read-only replicas

Question 16

Which TWO data types are supported in Cloud Spanner schemas?

Accepted Answer

ARRAY. ARRAY is a supported data type in Cloud Spanner, allowing you to store ordered lists of elements of the same primitive type (e.g., ARRAY, ARRAY). This is essential for modeling one-to-many relationships without requiring separate tables, and it integrates seamlessly with Cloud Spanner's query engine for array operations.

Answer

GEOMETRY

Answer

TEXT

Answer

TINYINT

Question 17

A team wants to enforce that all Compute Engine disks must be encrypted with Customer-Managed Encryption Keys (CMEK) stored in Cloud Key Management Service (KMS). Which TWO steps should they take? (Choose two.)

Accepted Answer

Apply an organization policy 'constraints/compute.requireCmek' at the desired level.. The organization policy constraint 'constraints/compute.requireCmek' enforces that all new Compute Engine disks in the specified hierarchy must be encrypted with a Customer-Managed Encryption Key (CMEK) from Cloud KMS. This policy prevents the creation of unencrypted disks or disks encrypted with Google-managed keys, ensuring compliance with security requirements.

Answer

Use gcloud commands to encrypt all existing disks with the KMS key.

Answer

Enable the Cloud KMS API in each project where the policy is enforced.

Answer

Grant the cloudkms.cryptoKeyEncrypterDecrypter role to the Compute Engine service account.

Question 18

A team uses Cloud Deploy to manage deployments to GKE across dev, staging, and prod. They want to implement a canary deployment strategy that automatically progresses based on latency metrics and includes a manual approval step before the full rollout. Which three Cloud Deploy features should they use together?

Accepted Answer

Canary deployment strategy. Cloud Deploy's canary deployment strategy allows you to progressively shift traffic to a new version, which aligns with the requirement for a gradual rollout. Option C is correct because SLO-based verification uses latency metrics (e.g., from Cloud Monitoring) to automatically determine whether the canary should progress, meeting the need for automated progression based on latency. Option E is correct because a manual approval gate can be inserted before the final full rollout, satisfying the requirement for a manual approval step.

Answer

Blue/green strategy

Answer

Automated rollback

Question 19

A team uses Cloud Build to build and deploy a Go application to GKE. They need to inject the Git commit SHA as an environment variable in the deployment. Which THREE steps should they take?

Accepted Answer

Grant the Cloud Build service account permission to update the Deployment. The Cloud Build service account needs the `container.deployments.update` permission (or a role like `roles/container.developer`) to modify the Deployment object in GKE. Without this IAM permission, the `kubectl set env` command in the build step will fail with a forbidden error, even if the image was successfully deployed.

Answer

Use Cloud Deploy instead of kubectl

Answer

Create a new Docker image tag with the commit SHA

Question 20

A DevOps engineer is designing a landing zone for a large enterprise. Which THREE components are essential for a well-architected landing zone? (Choose THREE.)

Accepted Answer

A shared VPC project to host common network resources.. A landing zone typically includes a shared VPC for network connectivity, a centralized logging project for audit logs, and a security project for centralized security services like Cloud Armor and Security Command Center.

Answer

A single billing account per team.

Answer

A separate project per developer for sandbox environments.