PCDE Manage a solution that can span multiple database technologies Practice Test 14 — 15 Questions

Question 1

A financial services company uses Cloud Spanner for transaction processing. They need to capture real-time changes from the database to stream to a downstream analytics system. Which THREE services or features can achieve this?

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

Accepted Answer

Cloud Pub/Sub. Spanner change streams are correct because they capture row-level mutations in real time directly from Cloud Spanner. Cloud Pub/Sub is correct as it provides a fully managed messaging service that ingests and delivers change events from Spanner change streams to downstream systems with at-least-once delivery and low latency. Cloud Dataflow is correct because it can process and transform the change stream events in real time, enabling streaming analytics or integration with other services. Together, these three services form a complete pipeline: Spanner change streams capture changes, Pub/Sub transports them, and Dataflow processes them for the analytics system.

Answer

Cloud SQL for PostgreSQL

Answer

Bigtable replication

Question 2

A company is using Memorystore for Redis as a session store. They need to scale horizontally to handle increasing traffic and ensure high availability with automatic failover. Which TWO actions should they take?

Accepted Answer

Enable Redis Cluster mode (sharding). Option C is correct because enabling Redis Cluster mode (sharding) in Memorystore for Redis distributes data across multiple shards, allowing the instance to scale horizontally to handle increasing traffic beyond the limits of a single node. Option D is correct because the Standard tier provides a primary and replica configuration with automatic failover, which is exactly what is needed to ensure high availability for the session store. Option A is incorrect because manually creating multiple standalone instances and routing traffic yourself does not provide automatic failover or a managed scaling solution. Option B is incorrect because Persistent Disk is not a Memorystore for Redis feature; Memorystore is an in-memory service and persistence is not configured via Persistent Disk. Option E is incorrect because the Basic tier runs on a single node with no replication or automatic failover, so it cannot meet the high availability requirement.

Answer

Create multiple standalone instances and route traffic manually

Answer

Use Persistent Disk for data persistence

Answer

Use the Basic tier

Question 3

An engineer needs to create a cross-region read replica for a Cloud SQL for MySQL instance to improve read scalability and provide disaster recovery. What must be configured on the primary instance to support cross-region replication?

Accepted Answer

Enable binary logging on the primary instance.. Cross-region replication for Cloud SQL for MySQL relies on MySQL's native binary log (binlog) based replication. Enabling binary logging on the primary instance records all data changes in binary log files, which the read replica in another region uses as the source for applying changes. Without binary logging enabled, the primary instance cannot provide the change stream necessary for cross-region replication to function.

Answer

Enable automated backups and point-in-time recovery.

Answer

Configure a Cloud VPN between the regions.

Answer

Set the primary instance to use MySQL 8.0.

Question 4

A company is using Cloud SQL and wants to automatically increase storage when disk usage reaches a threshold. What should they configure?

Accepted Answer

Enable 'auto-storage increase' in the instance settings.. Cloud SQL provides a built-in 'auto-storage increase' setting that, when enabled, automatically increases the instance's storage capacity when disk usage reaches a predefined threshold (typically 90% or when free space drops below a certain amount). This eliminates the need for manual intervention or custom automation, ensuring high availability and preventing out-of-disk errors.

Answer

Use Active Assist recommendations to manually resize.

Answer

Set up a Cloud Monitoring alert to manually increase storage when usage exceeds 80%.

Answer

Configure a Cloud Function to resize the disk via API when threshold is reached.

Question 5

A Cloud Bigtable cluster is currently using HDD storage. The team wants to switch to SSD for better performance. What is the correct approach?

Accepted Answer

Create a new cluster in the same instance with SSD, then delete the old HDD cluster.. In Cloud Bigtable, storage type is a property of the cluster, not the instance. You cannot change the storage type of an existing cluster. The correct approach is to add a new cluster with SSD storage to the same instance, then delete the original HDD cluster. This allows you to migrate without data loss or downtime, as data is replicated across clusters in the same instance.

Answer

Use the gcloud bigtable clusters update command with the --storage-type flag.

Answer

Export the table to Cloud Storage, delete the instance, create a new one with SSD, and import.

Answer

Delete the existing cluster and recreate it with SSD. Data is retained in the instance.

Question 6

A Memorystore for Redis instance is running out of memory. The application can tolerate some data loss but not crashes. The team wants to ensure the instance remains available without manual intervention. Which eviction policy should they configure?

Accepted Answer

allkeys-lru. (allkeys-lru) is correct because it allows Redis to evict the least recently used keys from the entire keyspace when memory is full, which keeps the instance available without crashing. Since the application can tolerate some data loss but not crashes, this policy ensures memory pressure is relieved automatically, preventing out-of-memory errors that would cause the instance to become unavailable.

Answer

volatile-lru

Answer

volatile-ttl

Answer

noeviction

Question 7

An engineer needs to restore a Cloud Spanner database from a backup that was taken 2 hours ago. The backup is stored in Cloud Storage. What steps are required?

Accepted Answer

Use gcloud spanner databases restore --backup= --destination-database=. To restore a Cloud Spanner database from a backup, use the `gcloud spanner databases restore` command and specify the backup ID and destination database. This is the correct method. Import/export uses Cloud Storage for moving data, but restoring a backup is a separate operation and cannot be done with the import command.

Answer

Create a new instance and use gcloud spanner instances restore.

Answer

Use gcloud spanner databases import from the Cloud Storage backup file.

Answer

Restore is not possible; you must use point-in-time recovery.

Question 8

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 a serverless, NoSQL document database built for mobile and web apps, offering real-time listeners that push data changes to connected clients instantly and built-in offline persistence via local caching. These features directly satisfy the requirement for real-time synchronization across users plus offline support without custom sync code.

Answer

Bigtable

Answer

Cloud SQL

Answer

Cloud Spanner

Question 9

Your Cloud SQL for MySQL instance is running low on storage. You need to increase the storage size without downtime. What should you do?

Accepted Answer

Edit the instance and increase the storage size; it will be applied online.. Cloud SQL for MySQL supports online storage increases. When you edit the instance and increase the storage allocation, the operation is applied without requiring a restart or causing downtime. The underlying infrastructure uses live migration and dynamic volume expansion to make the additional capacity available immediately while the instance continues serving traffic.

Answer

You cannot increase storage online; you must create a new instance.

Answer

Create a clone of the instance with larger storage and switch traffic.

Answer

Enable automatic storage increase and it will happen automatically.

Question 10

Your Memorystore for Redis instance needs to survive a zonal failure with minimal data loss. Which feature should you use?

Accepted Answer

Use a Standard tier instance with replication across zones within the same region.. A Standard tier Memorystore for Redis instance with replication across zones provides automatic failover to a replica in a different zone, ensuring high availability and minimal data loss during a zonal failure. The Standard tier uses synchronous replication within the region, so data written to the primary is replicated to the cross-zone replica before acknowledging the write, which minimizes data loss to only in-flight transactions that were not yet committed.

Answer

Use a Basic tier instance and schedule periodic exports to Cloud Storage.

Answer

Enable persistence with RDB snapshots stored in Cloud Storage.

Answer

Create a cross-region replica (read replica in another region).

Question 11

A Cloud SQL for PostgreSQL read replica is experiencing replication lag of several minutes. You need to reduce the lag. What is the most effective solution?

Accepted Answer

Increase the CPU and memory of the read replica to speed up applying changes.. Replication lag in Cloud SQL for PostgreSQL read replicas is often caused by the replica being unable to keep up with the rate of write-ahead log (WAL) apply from the primary. Increasing the CPU and memory of the read replica directly improves its ability to replay WAL records faster, reducing the lag. This is the most effective solution as it addresses the bottleneck at the replica side without impacting the primary instance.

Answer

Disable automated backups on the primary to free up resources.

Answer

Promote the replica to a standalone instance and recreate the replica.

Answer

Increase the CPU and memory of the primary instance.

Question 12

You are building a global application that requires strong consistency across regions. The application needs to support SQL queries and horizontal scaling. Which database service should you choose?

Accepted Answer

Cloud Spanner

Answer

Cloud SQL with cross-region replicas

Answer

Cloud Bigtable

Answer

Firestore

Question 13

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.

Question 14

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.. Option A is correct because Cloud Spanner schema changes are applied asynchronously in the background, and depending on the size of the database and the nature of the change, they can take from minutes up to hours to complete. Option C is correct because ALTER TABLE statements in Cloud Spanner are non-blocking: existing reads and writes continue to work while the schema change is being applied, so the database remains fully in use. Option B is incorrect because Cloud Spanner never requires an instance restart to apply schema changes. Option D is incorrect because Cloud Spanner supports both adding and dropping columns via ALTER TABLE. Option E is incorrect because creating a secondary index is an online, non-blocking operation that does not take the table offline.

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 15

Which THREE metrics should you set up alerts for to proactively monitor the health of a Cloud SQL for MySQL instance? (Choose 3)

Accepted Answer

Replication lag (for instances with replicas). Option A (Replication lag for instances with replicas) is correct because Cloud SQL for MySQL exposes the mysql.replication.seconds_behind_master (or replication_lag) metric, and a growing lag indicates the replica is falling behind the primary, threatening read consistency and failover readiness. Option C (CPU utilization > 80%) is correct because Cloud SQL publishes the database/cpu/utilization metric, and sustained high CPU on the instance can signal query contention, missing indexes, or undersized tier, making it a key proactive health alert. Option E (Disk usage) is correct because Cloud SQL reports database/disk/bytes_used versus the instance's storage capacity, and running out of disk space causes write failures and instance outages, so alerting before the threshold is essential. Option B (Number of queries per second) is not a health indicator by itself since QPS varies with normal workload and has no universal threshold for alerting. Option D (Network throughput) is likewise workload-dependent and does not directly reflect instance health problems, so it is not one of the three recommended alert metrics.

Answer

Number of queries per second

Answer

Network throughput