PCDBE Sample Questions

PCDBE Sample Questions & Answers

Free Professional Cloud Database Engineer practice questions with worked answers and explanations. See how the ExamJungle simulator prepares you — then jump into the full test.

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Showing 9 of 19 free samples.

  1. Question 1Beginner

    Design scalable and highly available cloud database solutions · Evaluate database high availability and disaster recovery options

    True or False: When a Cloud SQL for MySQL instance is configured for high availability (HA), read requests are automatically load-balanced between the primary and standby instances to improve read throughput.

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    Correct answer: A

    This statement is false. The purpose of the standby instance in a Cloud SQL HA configuration is solely for failover. It is a 'hot standby' that takes over if the primary instance becomes unavailable. It does not serve read traffic. To scale read throughput, you must create one or more separate read replicas.

  2. Question 2Intermediate

    Deploy scalable and highly available databases in Google Cloud · Provision high availability database solutions in Google Cloud

    Your company runs a critical order processing system on a regional Cloud SQL for PostgreSQL instance. The business has defined a Recovery Point Objective (RPO) of zero and a Recovery Time Objective (RTO) of less than 5 minutes for regional failures. You have already configured the instance for high availability (HA). What additional step is required to meet these business requirements?

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    Correct answer: A

    The standard HA configuration for Cloud SQL protects against zonal failures, not regional failures. To meet a low RTO for a regional disaster, you must have a replica in another region. A cross-region read replica serves this purpose. While replication is asynchronous (meaning RPO is not strictly zero, but very close), it is the standard and required Cloud SQL pattern for regional DR. The promotion must be handled manually or via automation scripts, as it's not an automatic process like zonal HA failover.

  3. Question 3Beginner

    Manage a solution that can span multiple database solutions · Assess slow running queries and identify missing indexes

    You are a database administrator for an online retailer. During a performance audit of your Cloud SQL for MySQL database, you discover several long-running queries that are causing CPU contention. The Query Insights dashboard shows that these queries are performing full table scans on a large products table. The queries typically filter products by category and is_active status. What is the most effective and efficient way to resolve this performance issue?

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    Correct answer: A

    The problem describes queries filtering by two specific columns, which are causing full table scans. This is a classic indicator of a missing index. A composite index on the columns used in the WHERE clause (category and is_active) will allow the database to directly look up the required rows instead of scanning the entire table, which is the most direct and efficient solution.

  4. Question 4Intermediate

    Design scalable and highly available cloud database solutions · Design scalable, highly available, and secure databases

    A gaming company uses Firestore in Native Mode to store player profiles and inventory. They are designing a new feature that requires retrieving all players who possess a specific rare item and have a skill level greater than 90. The players collection contains millions of documents. The development team is concerned about query performance and cost. Which Firestore feature should they use to implement this query efficiently?

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    Correct answer: A

    Firestore requires an index for every query it executes. A simple query on one field will use a default single-field index. However, this query involves a range filter (skill_level > 90) and an array membership filter (inventory contains rare_item). To perform this query efficiently, Firestore requires a manually created composite index that includes both fields. Without it, the query would be rejected by the Firestore API.

  5. Question 5Intermediate

    Migrate data solutions · Plan and perform database migration, including fallback plans and schema conversion

    You are migrating a 10 TB on-premises MySQL 5.7 database to Cloud SQL for MySQL 8.0. The business requires the migration to have near-zero downtime. You plan to use the Database Migration Service (DMS). During the planning phase, you need to identify the correct sequence of steps to perform the migration and cutover. What is the correct order of operations?

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    Correct answer: A

    This sequence follows the Google-recommended best practices for a near-zero downtime migration with DMS. You first set up connectivity, then start the continuous job which handles the initial dump and ongoing replication. It's crucial to monitor the replication delay to ensure the target is caught up before cutover. The cutover itself involves stopping the application to prevent new writes to the old source, promoting the Cloud SQL instance to a standalone, writable server, and finally, pointing the application to the new database.

  6. Question 6Advanced

    Manage a solution that can span multiple database solutions · Scale database instances based on current and upcoming workload

    A financial analytics platform uses AlloyDB for PostgreSQL to serve a mix of transactional queries and complex, real-time analytical dashboards. During peak trading hours, dashboard loading times increase significantly. Initial investigation using Query Insights reveals that the analytical queries are consuming a large amount of CPU and I/O, impacting the transactional workload. The platform must maintain low latency for both workloads. What is the most effective way to isolate the analytical workload and improve overall performance using AlloyDB's features?

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    Correct answer: A

    AlloyDB's architecture is designed for this exact scenario. A read pool provides one or more dedicated, compute-only nodes that can be scaled independently from the primary instance. They access the same shared storage layer, ensuring they are always up-to-date with minimal replication lag. By directing the analytical queries to the read pool's endpoint, you isolate their compute and memory usage from the primary instance, allowing both transactional and analytical workloads to perform optimally without interfering with each other.

  7. Question 7Intermediate

    Manage a solution that can span multiple database solutions · Design database backup and recovery solutions

    You are managing a Cloud SQL for SQL Server instance that hosts a critical business application. The development team needs to perform a major application upgrade that includes significant schema changes and data modifications. You must ensure that you can quickly revert the database to its pre-upgrade state if the deployment fails. The entire process, including a potential rollback, must be completed within a 30-minute window. What is the most efficient method to prepare for this upgrade?

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    Correct answer: B

    Cloning a Cloud SQL instance is a fast operation that creates a new, fully independent instance with a copy of the data from a specific point in time. This is the ideal approach for creating a pre-upgrade snapshot. The rollback process is also very fast: simply redirect the application's connection string to the clone's IP address. This avoids the lengthy data restore process and easily meets the 30-minute window.

  8. Question 8Intermediate

    Design scalable and highly available cloud database solutions · Determine how applications will connect to the database

    A startup is building a serverless application using Cloud Functions and Firestore. To control costs, they want to implement a mechanism that prevents a single function invocation from performing an excessive number of database operations. For example, they want to cap the number of document writes per invocation to 100. How can they enforce this rule across their application?

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    Correct answer: B

    This is the correct and most practical approach. The application logic within the Cloud Function is responsible for building the database request. By using a batched write (WriteBatch), the function can add multiple operations to the batch and, before calling .commit(), check the size of the batch. If it exceeds the defined limit (e.g., 100 writes), the function can throw an error or handle it appropriately. This enforcement happens within the application code itself.

  9. Question 9Beginner

    Design scalable and highly available cloud database solutions · Evaluate appropriate database solutions on Google Cloud

    You are designing a database solution for a new mobile application that requires offline data access and automatic synchronization when the device comes back online. The data model is document-based and will be accessed directly by the client application. Which Google Cloud database and client-side feature set should you choose?

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    Correct answer: A

    Firestore is specifically designed for this use case. Its mobile and web client SDKs have built-in capabilities for offline data persistence. The SDK maintains a local cache of the data. When the application is offline, it reads from and writes to this cache. When connectivity is restored, the SDK automatically synchronizes the local changes with the Firestore backend.

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