PCDE Practice Exam 2 — 20 Questions

Question 1

A company is designing a mobile application backend that requires real-time synchronization across users and offline support. Which Google Cloud database service is most suitable?

Accepted Answer

Firestore. Firestore is designed for real-time sync, offline support, and mobile/web applications. It provides real-time listeners and offline data persistence.

Answer

Bigtable

Answer

Cloud SQL

Answer

Cloud Spanner

Question 2

A company has a Cloud SQL for PostgreSQL instance with a read replica in another region. They want to perform disaster recovery testing without affecting the primary. What should they do?

Accepted Answer

Promote the read replica to a standalone instance and use it for testing.. Promoting the read replica to a standalone instance detaches it from the primary, creating an independent writable Cloud SQL instance. This allows you to perform disaster recovery testing (e.g., failover validation, data integrity checks) without any impact on the primary instance, as the replica no longer replicates changes from the primary.

Answer

Use the replica as a failover target; testing is not allowed.

Answer

Enable point-in-time recovery on the replica and restore to a new instance.

Answer

Create a clone of the primary instance and test on that.

Question 3

A company wants to store and analyze data with BigQuery. They have customers in Europe and need to comply with GDPR data residency requirements. What should they do to ensure data stays within the European Union?

Accepted Answer

Create the dataset with the location set to 'EU'.. BigQuery enforces data residency at the dataset level. When you create a dataset with the location set to 'EU', all tables, views, and data within that dataset are physically stored in a Google Cloud region within the European Union. This ensures compliance with GDPR data residency requirements, as data will not be moved or replicated outside the EU without explicit user action.

Answer

Use the default dataset location and rely on BigQuery's automatic compliance.

Answer

Set the query job location to 'EU' for all queries.

Answer

Choose a dataset location of 'us-central1' for performance.

Question 4

A team is migrating an on-premises PostgreSQL database to Cloud SQL using DMS. They want the migration job to continuously replicate changes after the initial dump. Which type of migration job should they create?

Accepted Answer

Continuous migration job. DMS offers 'one-time' for single dump and 'continuous' for ongoing CDC. Continuous jobs replicate changes after dump.

Answer

One-time migration job

Answer

Scheduled export job

Answer

Bulk load job

Question 5

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 6

An engineer needs to connect Database Migration Service to a source MySQL database that has only a private IP address. The Cloud SQL destination is also private. What is the recommended method for DMS to connect to the source?

Accepted Answer

Use VPC peering or Cloud SQL Auth Proxy. For private IP sources, VPC peering or Cloud SQL Auth Proxy can be used. Auth Proxy is recommended for secure connectivity without public IP exposure.

Answer

Use a Cloud VPN tunnel with static IP

Answer

Use Cloud NAT to provide outbound connectivity

Answer

Use the source database's public IP with IP allowlisting

Question 7

A team needs to migrate a large Teradata data warehouse to BigQuery. They want to automatically convert Teradata DDL and BTEQ scripts to BigQuery-compatible SQL. Which Google Cloud service should they use?

Accepted Answer

Schema Conversion Tool (SCTS). Schema Conversion Tool (SCTS) is designed for heterogeneous migrations, converting DDL and scripts from sources like Teradata to BigQuery.

Answer

BigQuery Data Transfer Service

Answer

Database Migration Service (DMS)

Answer

Cloud Dataflow

Question 8

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 9

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 10

What is the maximum backup retention period for Cloud Spanner backups?

Accepted Answer

365 days. Cloud Spanner allows backups to be retained for up to 365 days.

Answer

730 days

Answer

90 days

Answer

30 days

Question 11

A Cloud SQL for PostgreSQL instance needs to achieve a recovery point objective (RPO) of less than 1 minute and a recovery time objective (RTO) of less than 2 minutes in the event of a zone failure. Which disaster recovery strategy should be used?

Accepted Answer

Configure Cloud SQL HA (high availability) with a standby in a different zone.. Cloud SQL HA configuration provides automatic failover to a standby in a different zone within the same region, with RPO near zero and RTO typically under 60 seconds. Cross-region read replicas have RPO equal to replication lag (could be minutes) and RTO of minutes due to manual promotion. Cross-region backup restore has RPO equal to backup age (hours) and RTO of hours. Point-in-time recovery (PITR) is for within-region data recovery, not zone failure failover.

Answer

Perform regular backups to Cloud Storage and restore in a different zone.

Answer

Enable cross-region replication using a read replica.

Answer

Enable point-in-time recovery (PITR) with transaction log backups.

Question 12

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 13

A Cloud Spanner database is experiencing high CPU utilization on one node. Users report slow queries. The table uses a UUID primary key. What is the most effective action?

Accepted Answer

Use a hash key prefix to distribute writes.. A hash key prefix can distribute writes more evenly across nodes, preventing hot spots that cause high CPU on a single node. Adding nodes may not resolve a hot spot.

Answer

Add a database index on frequently queried columns.

Answer

Convert the UUID to a monotonically increasing integer.

Answer

Increase the number of nodes in the instance.

Question 14

A company uses Cloud Monitoring to create an SLO for a service. They want to define a request-based SLO with a ratio of good requests to valid requests. Which of the following is a valid way to define the SLI in Cloud Monitoring SLOs?

Accepted Answer

Select a metric for good requests and a separate metric for total valid requests, then define the SLI as good-request-count / valid-request-count. Cloud Monitoring SLOs require two metrics: one for good events and one for total valid events. The ratio is good/total. The correct configuration uses separate metrics for good and valid requests.

Answer

Use a distribution metric for latency and set a threshold for good latency

Answer

Create a custom metric for requests and use Cloud Monitoring's built-in availability SLI for HTTP services

Answer

Use a single metric that indicates success (1 for success, 0 for failure) and set a threshold filter

Question 15

The exhibit shows query metadata for a query that scans 10 GB. Given the table is 100 GB and partitioned by hire_date, why did the query scan 10 GB and not less?

Accepted Answer

The filter on hire_date is not selective enough to prune most partitions. Partition pruning in Google BigQuery depends on the selectivity of the filter predicate. If the filter on `hire_date` matches a large number of partitions (e.g., filtering on a range that covers 10 GB out of 100 GB), the query scans exactly those partitions. The table is 100 GB and partitioned by `hire_date`, so a 10 GB scan implies the filter pruned 90 GB of partitions but was not selective enough to reduce the scan further—e.g., the predicate may be a broad range or lack a precise equality condition.

Answer

Clustering on department is not being used because the query has ORDER BY

Answer

The query uses GROUP BY, which forces a full table scan

Answer

The table is not clustered properly

Question 16

A company runs Cloud SQL for PostgreSQL and wants to automatically increase storage when usage reaches a threshold. What should they enable?

Accepted Answer

Enable storage auto-increase in instance settings. Cloud SQL has a built-in 'auto-storage increase' feature that automatically adds storage when necessary, avoiding manual intervention.

Answer

Create a cron job to resize via gcloud

Answer

Configure automated backups

Answer

Use Active Assist recommendations to resize

Question 17

A team uses Kustomize to manage environment-specific configurations for their GKE deployments. They have a base overlay and overlays for dev, staging, and prod. Which command should they use to generate the final Kubernetes manifests for the staging environment?

Accepted Answer

kustomize build staging/. The `kustomize build staging/` command processes the Kustomize overlay located in the `staging/` directory, which includes a `kustomization.yaml` file that references the base overlay and applies environment-specific patches, configMapGenerator entries, and namespace settings. This generates the final Kubernetes manifests for the staging environment without applying them to a cluster. The `kustomize` CLI tool is the standard way to render Kustomize overlays, and it is the correct command for generating manifests as part of a CI/CD pipeline.

Answer

kubectl kustomize staging/

Answer

skaffold build --kustomize staging/

Answer

kubectl apply -k staging/

Question 18

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 19

Your Cloud SQL for MySQL instance is experiencing intermittent performance degradation. You suspect that the issue is due to a sudden spike in connections from a specific application. Which metric and monitoring approach would best help you correlate the connection spike with performance degradation?

Accepted Answer

Monitor 'cloudsql.googleapis.com/database/mysql/threads/threads_connected' and correlate with CPU utilization and query latency.. The 'threads_connected' metric directly measures the number of active connections to the MySQL instance. Correlating this with CPU utilization and query latency allows you to pinpoint whether a sudden spike in connections is causing resource contention and degraded query performance, which is the exact scenario described.

Answer

Monitor 'cloudsql.googleapis.com/network/received_bytes_count' and compare with connection count.

Answer

Monitor 'cloudsql.googleapis.com/database/mysql/replication/seconds_behind_master' and compare with query latency.

Answer

Monitor 'cloudsql.googleapis.com/instance/uptime' and check for instance restarts during degradation.

Question 20

You are designing disaster recovery for a globally distributed application using Cloud Spanner with a multi-region configuration. The application requires an RPO of 0 and an RTO of less than 5 seconds in the event of a full region failure. Which Spanner configuration provides these guarantees?

Accepted Answer

A multi-region Spanner instance with two read-write regions and one witness region.. A multi-region configuration with a leader region and at least two voting regions provides synchronous replication and automatic failover. Regional failover occurs within seconds, preserving zero data loss.

Answer

A single-region Spanner instance with a read replica in another region.

Answer

A multi-region Spanner instance with one read-write region and two read-only regions.

Answer

A dual-region Spanner instance using default leader placement.