PCDE Manage a solution that can span multiple database technologies Practice Test 9 — 15 Questions

Question 1

A developer is setting up a Memorystore for Redis instance and needs to restrict access to only a specific Compute Engine VM in the same VPC network. Which configuration should they use?

Accepted Answer

Configure the Memorystore instance with a firewall rule that allows only the VM's internal IP. Memorystore for Redis uses Private Service Access and requires authorizing a VPC network to access the instance. After authorizing the VPC network, you can restrict access to a specific Compute Engine VM by applying a firewall rule in that VPC that allows traffic from only that VM's internal IP to the Memorystore instance. This is the most granular control available without using additional authentication like AUTH.

Answer

Use Cloud Armor to whitelist the VM's external IP

Answer

Use the AUTH password and share it only with the VM

Answer

Place the Redis instance in a separate VPC and peer only with the VM's VPC

Question 2

A company has a Cloud SQL for MySQL instance with a cross-region read replica for disaster recovery. During a regional outage, they need to promote the read replica to a standalone instance as quickly as possible. What is the correct procedure?

Accepted Answer

Use the gcloud sql instances promote-replica command on the replica. Promoting a read replica makes it a standalone instance. It can be done via the Cloud Console or gcloud command. The promotion is immediate, but the original primary may still be active if not stopped.

Answer

Create a backup of the replica and restore it as a new instance

Answer

Delete the read replica and restore a backup from the primary as a new instance

Answer

Stop replication on the replica by issuing STOP SLAVE on the instance

Question 3

A company uses Cloud Spanner for a global application. They need to capture real-time changes to certain tables for downstream processing. Which two services or features can be used together to achieve this? (Choose TWO.)

Accepted Answer

Spanner change streams. Spanner change streams capture transactional changes in near real-time. Dataflow can read from change streams and stream the changes to downstream systems like Pub/Sub, BigQuery, or Cloud Storage.

Answer

Cloud Pub/Sub Lite

Answer

Cloud SQL for PostgreSQL

Answer

Cloud Functions

Question 4

A company runs a Memorystore for Redis cluster with standard tier (for replication). They need to ensure high durability of session data and be able to recover from a complete zone failure. Which three actions should they take? (Choose THREE.)

Accepted Answer

Schedule regular exports of the instance data to Cloud Storage using gcloud. To ensure high durability and recovery from a complete zone failure for a Memorystore for Redis cluster with standard tier (replication enabled): Option A: Regular exports to Cloud Storage provide point-in-time backups that can be restored in a different zone if needed. Option B: Cross-region replication creates a replica in another region, allowing failover if the primary zone fails. Option E: Setting up a second instance in a different zone with client-side replication allows the application to switch to the replica if the primary zone fails. Option C is incorrect because Redis Cluster with multiple shards is for horizontal scaling and does not inherently provide zone failure recovery or durability beyond what replication provides. Option D is incorrect because RDB persistence, while supported in Memorystore for Redis, only provides local recovery and does not protect against a complete zone failure; you need cross-zone or cross-region replication for that.

Answer

Use a Redis Cluster with multiple shards for horizontal scaling

Answer

Enable RDB persistence on the primary instance

Question 5

A company wants to migrate from an on-premises MySQL database to Cloud SQL. They need to minimize downtime and ensure data consistency. Which two steps should they include in the migration plan? (Choose TWO.)

Accepted Answer

Set up continuous replication from the on-premises database to the Cloud SQL instance using Database Migration Service. Database Migration Service (DMS) supports continuous replication using MySQL binary logs, enabling a near-zero-downtime migration by keeping the Cloud SQL instance synchronized with the on-premises database until cutover. Option D is correct because taking a consistent snapshot (e.g., using mysqldump with --single-transaction or a storage-level snapshot) at cutover ensures data consistency and provides a fallback point if the migration fails.

Answer

Create a read replica in the same region for validation before cutover

Answer

Use Cloud SQL's import functionality to load a mysqldump file

Answer

Disable binary logging on the on-premises database to reduce overhead

Question 6

A company runs an e-commerce application on Cloud SQL for MySQL. They need to recover the database to a specific point in time 15 minutes ago after an accidental data deletion. What must be configured beforehand?

Accepted Answer

Configure binary logging and set a PITR retention period. Point-in-time recovery (PITR) in Cloud SQL for MySQL relies on binary logging (binlog) to capture all write operations. To recover to a specific moment (e.g., 15 minutes ago), you must enable automated backups (which provide the base restore point) and configure binary logging with a retention period that covers the desired recovery window. Option C correctly specifies both requirements: binary logging must be enabled, and a PITR retention period (e.g., 1–7 days) must be set to retain the necessary binlog files for replay.

Answer

Create a cross-region replica for failover

Answer

Enable automated backups only

Answer

Set up an on-demand backup every hour

Question 7

A Cloud SQL for PostgreSQL instance is experiencing a surge in read traffic. The team wants to offload read queries without affecting write latency. What should they do?

Accepted Answer

Create a same-region read replica. Creating read replicas allows distributing read traffic, reducing load on the primary instance for writes. Read replicas are the standard solution for scaling read workloads.

Answer

Enable automated backups

Answer

Create a cross-region read replica

Answer

Increase the CPU of the primary instance

Question 8

A Cloud SQL for MySQL instance's storage utilization has reached 95%. The database is 5 TB and needs to grow. The operations team tries to increase storage via gcloud but receives an error. What is the likely cause?

Accepted Answer

The instance is at the maximum storage limit for its machine tier. Cloud SQL allows online storage increases but with limits: the maximum storage cannot exceed 30 TB, and the increase must be done in increments. However, the error is likely because the instance is using the maximum allowed storage for its tier, or the storage cannot be shrunk. But the most common issue is that the instance has an on-demand backup or restore operation in progress, which blocks resize. Another possibility is that the storage is already at the maximum for that machine type. However, the question implies a common misconfiguration: the instance may have a read replica that is replicating from it, and storage resize is not allowed if the replica is in a different region? Actually, storage resize is allowed regardless. More likely: the user has reached the maximum storage size for the current tier (e.g., db-n1-standard-8 supports up to 10 TB). The correct answer is tier storage limit.

Answer

The storage resize operation is only allowed during maintenance windows

Answer

The instance has binary logging enabled, which prevents storage increase

Answer

The instance has automatic storage increase disabled

Question 9

A company uses Cloud Spanner for a global inventory application. They need to add a new index to a large table without downtime. What is the recommended approach?

Accepted Answer

Use CREATE INDEX; Spanner handles it as a non-blocking operation. Cloud Spanner's CREATE INDEX operation is inherently non-blocking; it performs the index backfill as a background process without locking the table or blocking reads and writes. This allows the index to be added to a large table with zero downtime, as Spanner manages the consistency and availability of the data throughout the operation.

Answer

Create the index using ALTER TABLE with 'ONLINE' clause

Answer

Use gcloud spanner databases ddl update with --async flag

Answer

Take a backup, create index on a new instance, and switch traffic

Question 10

A Cloud Bigtable instance has a hot spot causing performance degradation. Which tool helps identify the hot spot?

Accepted Answer

Key Visualizer. Key Visualizer is a built-in Bigtable tool that visualizes access patterns and helps identify hot spots (uneven load across row keys).

Answer

Cloud Monitoring dashboard

Answer

Cloud Logging

Answer

Bigtable Admin API

Question 11

A Memorystore for Redis instance is running out of memory. The application uses a mix of cache and session data. Which eviction policy should be chosen to minimize cache misses while ensuring session data is not evicted?

Accepted Answer

volatile-ttl. The volatile-ttl policy evicts keys with a TTL set, prioritizing those with the shortest remaining TTL. Since session data typically has a TTL and cache data may or may not, this policy allows you to protect session data by assigning it a longer TTL, while cache data with shorter TTLs is evicted first, minimizing cache misses.

Answer

noeviction

Answer

allkeys-lru

Answer

allkeys-random

Question 12

A company uses Firestore in Native mode. They have a collection with 1 million documents and frequently run queries that filter on two fields: status and createdAt. The queries are slow. What should the team do?

Accepted Answer

Create a composite index on (status, createdAt). Firestore creates single-field indexes automatically but for multi-field queries, a composite index must be created manually. Without it, queries may be slow or fail.

Answer

Create an index exemption for the status field

Answer

Use the Datastore mode instead

Answer

Add an index exemption for the createdAt field

Question 13

A company wants to monitor Cloud SQL database latency for read replicas and set up an alert if the replica lag exceeds 30 seconds. Which metric should be used?

Accepted Answer

cloudsql.googleapis.com/database/replication/replication_lag. The 'replication_lag' metric in Cloud SQL measures the lag between primary and read replica. It is the correct metric to set alerts for replica lag.

Answer

cloudsql.googleapis.com/database/postgresql/num_backends

Answer

cloudsql.googleapis.com/database/cpu/utilization

Answer

cloudsql.googleapis.com/database/disk/bytes_used

Question 14

An e-commerce platform uses Cloud Bigtable for session data. They need to ensure that if one zone fails, the data is still available with eventual consistency. What should they configure?

Accepted Answer

Enable Bigtable replication across zones within the same region. Bigtable replication across zones provides high availability with eventual consistency (async replication). This meets the requirement of surviving a zone failure.

Answer

Create a Cloud Bigtable cluster with multiple nodes

Answer

Export Bigtable tables to Cloud Storage periodically

Answer

Use Cloud Bigtable HDD storage for durability

Question 15

A gaming company uses Cloud Spanner to store player profiles and game state. They need to run a one-time analytic query on historical data that would take minutes and cannot impact production performance. What is the best approach?

Accepted Answer

Export the required data to BigQuery using Dataflow and run the query there. Exporting the data to BigQuery via Dataflow isolates the analytic workload from Cloud Spanner, ensuring zero impact on production performance. Cloud Spanner is designed for transactional workloads, not heavy analytic queries that take minutes, and BigQuery is purpose-built for such analytics. This approach also avoids consuming Spanner's CPU or memory resources, which could degrade real-time game state operations.

Answer

Create a read-only replica and query it

Answer

Use the gcloud spanner databases execute-sql command with --query-mode=read-only

Answer

Run the query using a read-only transaction with strong reads