PCD Deploy Scalable and Highly Available Databases in Google Cloud Practice Test 5 — 15 Questions

Question 1

An organization has a Cloud SQL for MySQL instance with 500 GB of data. They want to offload reporting queries that scan large portions of the database without impacting the primary instance's performance. Which solution should they implement?

Accepted Answer

Create a cross-region Cloud SQL read replica and direct reporting queries to it. Creating a cross-region read replica distributes read traffic and isolates reporting workloads from the primary. Cloud SQL read replicas are asynchronous and can be promoted if needed. For read-only queries, this is the correct approach.

Answer

Use Cloud SQL connection pooling to share connections

Answer

Upgrade the primary instance to a high-memory machine type

Answer

Enable automatic storage increase on the primary instance

Question 2

A company's Cloud Bigtable instance is experiencing high latency and increased error rates for write requests. The Key Visualiser shows that a single row key prefix receives the majority of writes, creating a hotspot. What is the BEST long-term solution to distribute writes more evenly?

Accepted Answer

Redesign the row key by salting with a hash or a more distributed prefix. To avoid hot spotting, row key design should incorporate a nonce or sharding prefix to distribute writes across tablets. Salting row keys with a calculated hash or a field with high cardinality spreads the load. The Key Visualiser confirms the hotspot; redesigning the key is the correct fix.

Answer

Add more nodes to the Bigtable cluster

Answer

Switch from SSD to HDD storage

Answer

Create a secondary Bigtable cluster in another region

Question 3

A development team wants to connect their Cloud SQL for PostgreSQL instance from a Compute Engine VM without exposing it to the public internet. They also want to avoid managing IP allowlists. Which method should they use?

Accepted Answer

Use Cloud SQL Auth Proxy. The Cloud SQL Auth Proxy provides secure, IAM-based access to Cloud SQL instances without requiring public IP or allowlists. It runs on the client and uses an encrypted tunnel. It works over Private IP if the VM is in the same VPC, but does not require it.

Answer

Use Private IP only

Answer

Configure a public IP with SSL enforcement

Answer

Assign a static IP to the VM and add it to authorized networks

Question 4

A startup is building a mobile application with real-time synchronization across user devices. They expect millions of users and need a NoSQL database with offline support and real-time listeners. Which database should they choose?

Accepted Answer

Firestore. Firestore is a flexible, scalable NoSQL database for mobile, web, and server development. It offers real-time synchronization, offline data persistence, and integrates with Firebase and Google Cloud. It is designed for this exact use case.

Answer

Cloud Bigtable

Answer

BigQuery

Answer

Cloud SQL

Question 5

An e-commerce platform uses Cloud Spanner for its inventory system. They notice that the processing units utilization is consistently above 90% during peak hours, causing increased read latency. They want to automatically scale capacity based on load. What should they configure?

Accepted Answer

Enable auto-scaling by setting min and max processing units with a high-priority CPU target. Cloud Spanner supports auto-scaling by configuring min and max processing units and a high-priority CPU target utilization. When utilization exceeds the target, Spanner automatically adds processing units up to the max. This is the correct approach.

Answer

Switch from processing units to nodes for better performance

Answer

Manually increase the number of nodes

Answer

Reduce the number of processing units to lower cost

Question 6

A financial services company requires a globally distributed database with strong consistency and sub-10 millisecond write latency across three continents. They anticipate 50 TB of transactional data. Which Google Cloud database should they deploy?

Accepted Answer

Cloud Spanner multi-region configuration. Cloud Spanner is the only Google Cloud database that provides global strong consistency, horizontal scaling, and low-latency reads and writes across regions. Multi-region configurations span continents and meet the requirements.

Answer

Firestore in multi-region mode

Answer

Cloud Bigtable with multi-cluster replication

Answer

Cloud SQL with cross-region replicas

Question 7

A team is deploying a Cloud SQL for PostgreSQL instance and needs to enforce that all connections use SSL/TLS. Which flag must they enable on the Cloud SQL instance?

Accepted Answer

require_ssl. The 'require_ssl' flag, when set to 'on', ensures that only SSL-encrypted connections are allowed. This is a database flag specific to Cloud SQL for PostgreSQL and MySQL.

Answer

ssl_enforcement

Answer

enforce_tls

Answer

cloudsql_ssl_only

Question 8

A manufacturing company collects time-series data from thousands of sensors and wants to store it in Cloud Bigtable. They need to design a row key that avoids hotspots and ensures even distribution of writes across tablets. Which row key design strategy is BEST?

Accepted Answer

Prefix the timestamp with a hash of the sensor ID. To avoid hotspots, the row key should start with a field that has high cardinality and even distribution. A common approach is to prepend a hash or a nonce derived from the timestamp or sensor ID to spread writes across tablets.

Answer

Use an inverted timestamp as the row key

Answer

Use the sensor ID as the first component of the row key

Answer

Use a single row key for all data from the same day

Question 9

A company has an AlloyDB cluster in us-central1. They want to replicate data to a secondary region for disaster recovery with a recovery point objective (RPO) of less than 1 second. Which AlloyDB feature should they use?

Accepted Answer

Use AlloyDB Omni to replicate to an instance in the secondary region. AlloyDB supports cross-region replication using AlloyDB Omni, which is a downloadable edition that can run on-premises or in other clouds. For cross-region DR, you can set up an AlloyDB Omni instance in another region that asynchronously replicates from the primary cluster. Note: The official AlloyDB cross-region replication uses AlloyDB Omni as the target. This is the correct feature.

Answer

Export the database to Cloud Storage and import in the secondary region

Answer

Configure a Cloud SQL for PostgreSQL read replica in the secondary region

Answer

Create a cross-region read replica in the secondary region

Question 10

A company's Firestore security rules are too permissive, allowing all users to read and write any document. They need to restrict access so that only authenticated users can read and write their own data. Which rule structure should they use?

Accepted Answer

Allow read/write if request.auth.uid == resource.data.user_id;. Firestore security rules can use `request.auth.uid` to verify the authenticated user's identity and `resource.data.user_id` to check ownership. The correct rule ensures that the authenticated user's UID matches the `user_id` field in the document.

Answer

Allow read/write if request.auth != null;

Answer

Allow read/write if request.auth != null && request.auth.uid == resource.id;

Answer

Allow read/write if request.auth.token.email == resource.data.email;

Question 11

A company needs to monitor the disk usage of their Cloud SQL instance to proactively increase storage before it runs out. They want to set an alert when disk usage exceeds 80%. Which metric should they use in Cloud Monitoring?

Accepted Answer

database/disk/bytes_used. Cloud SQL provides the `database/disk/bytes_used` metric, which represents the actual storage used. By setting an alert on this metric (e.g., as a percentage of total disk size), they can be notified when usage is high.

Answer

database/cpu/utilisation

Answer

database/disk/quota

Answer

database/memory/utilisation

Question 12

A company is deploying a Cloud Spanner instance for a global application. They need to minimize write latency for users in Asia, Europe, and North America while maintaining strong consistency. Which two configurations should they choose? (Choose two.)

Accepted Answer

Use nodes for compute capacity. Option A is correct because nodes provide dedicated compute and storage resources in Cloud Spanner, which are necessary to achieve low write latency and high throughput for a global application. Nodes scale linearly with performance, ensuring that write operations are processed quickly across multiple regions. For a multi-region instance, nodes are the only supported compute capacity option, as processing units are limited to regional instances.

Answer

Use a regional instance configuration

Answer

Use processing units for compute capacity

Answer

Enable auto-scaling with a high-priority CPU target

Question 13

A company is migrating an on-premises PostgreSQL database to Cloud SQL. They need to ensure high availability and minimize downtime during maintenance. They also want to enable IAM database authentication for enhanced security. Which three actions should they take? (Choose three.)

Accepted Answer

Create a Cloud SQL for PostgreSQL instance with regional HA configuration. Option A is correct because creating a Cloud SQL for PostgreSQL instance with regional HA configuration uses synchronous replication across two zones within the same region, providing automatic failover with minimal downtime. This ensures high availability and meets the requirement to minimize downtime during maintenance, as the standby instance takes over with no data loss.

Answer

Use Cloud SQL Auth Proxy for all connections

Answer

Create a cross-region read replica for failover

Question 14

A company is using Cloud Bigtable for a high-throughput write workload. They notice periodic latency spikes. Which two metrics should they monitor to diagnose the issue? (Choose two.)

Accepted Answer

Error count. Request latency directly measures performance. Error count indicates failures or throttling. CPU utilization and disk usage are less direct indicators for write spikes. However, the question asks for two metrics to diagnose latency spikes; the most relevant are request latency and error count.

Answer

Disk bytes used

Answer

Network throughput

Answer

CPU utilization

Question 15

A company uses Cloud SQL for MySQL with a single zone. They need high availability with automatic failover in under 60 seconds. What configuration should they use?

Accepted Answer

Enable regional HA by adding a standby in a different zone. Cloud SQL HA configuration creates a primary and a standby instance in different zones within the same region, using synchronous replication. Automatic failover occurs in under 60 seconds. Zonal HA is not a valid concept, and cross-region failover is not automatic.

Answer

Configure zonal HA with a standby in the same zone

Answer

Use AlloyDB with cross-region replication

Answer

Create a read replica in a different region