DBS-C01 Workload-Specific Database Design Practice Test 4 — 15 Questions

Question 1

A company runs a time-series application that collects sensor data from millions of IoT devices. The data is written in batches every minute and queried to generate hourly, daily, and monthly aggregates. The database must support high ingestion rates and efficient storage. Which database service is most appropriate?

Accepted Answer

Amazon Timestream. Amazon Timestream is purpose-built for time-series data, offering a serverless architecture that automatically scales to handle high ingestion rates from millions of IoT devices. It optimizes storage by separating recent data (in memory) from historical data (in a magnetic store), and its built-in aggregation functions (e.g., `BIN`, `DATE_BIN`) efficiently compute hourly, daily, and monthly aggregates without manual partitioning or indexing.

Answer

Amazon DynamoDB with TTL

Answer

Amazon Redshift

Answer

Amazon RDS for PostgreSQL

Question 2

A financial services company is migrating an on-premises Oracle database to AWS. The database supports an OLTP application with complex joins, stored procedures, and requires high availability within a single Region. The company wants to minimize licensing costs and use a fully managed service. Which AWS database service should they choose?

Accepted Answer

Amazon Aurora PostgreSQL-Compatible Edition. Amazon Aurora PostgreSQL-Compatible Edition is the correct choice because it is a fully managed, high-availability database service that supports complex joins, stored procedures, and OLTP workloads while minimizing licensing costs. Aurora provides built-in replication across three Availability Zones, automatic failover, and up to 15 read replicas, meeting the high availability requirement without the licensing overhead of commercial databases like Oracle.

Answer

Amazon DynamoDB

Answer

Amazon RDS for Oracle

Answer

AWS Database Migration Service (DMS)

Question 3

A company is building a social network application that needs to store user profiles, friend relationships, and a feed of posts. The feed queries are complex, involving graph traversals (e.g., friends of friends). Which database is best suited for the relationship data?

Accepted Answer

Amazon Neptune. Amazon Neptune is a fully managed graph database service optimized for storing and querying highly connected data. It supports both property graph and RDF models, and it uses graph traversal languages like Gremlin and SPARQL, making it ideal for complex friend-of-friend queries and social network relationship data.

Answer

Amazon DynamoDB

Answer

Amazon RDS for MySQL

Answer

Amazon ElastiCache for Redis

Question 4

A company needs to store and query JSON documents that vary in structure. The application requires flexible schema, automatic indexing, and the ability to run complex aggregation pipelines. Which AWS database service should be used?

Accepted Answer

Amazon DocumentDB (with MongoDB compatibility). Amazon DocumentDB (with MongoDB compatibility) is the correct choice because it is purpose-built for storing and querying JSON-like documents with flexible schemas, automatically indexes fields, and supports MongoDB's aggregation pipeline for complex data transformations. This aligns directly with the requirements for varying document structures, automatic indexing, and aggregation capabilities.

Answer

Amazon DynamoDB

Answer

Amazon ElastiCache for Redis

Answer

Amazon RDS for PostgreSQL

Question 5

A company runs an analytics platform that queries billions of rows of sales data. Queries are complex and involve aggregations across multiple dimensions. The data is updated in bulk daily. Which service should be used as the primary data store?

Accepted Answer

Amazon Redshift. Amazon Redshift is the correct choice because it is a fully managed, petabyte-scale data warehouse optimized for complex analytical queries involving aggregations across multiple dimensions. Its columnar storage, massively parallel processing (MPP) architecture, and ability to handle bulk daily updates via COPY commands or INSERT operations make it ideal for querying billions of rows of sales data.

Answer

Amazon DynamoDB

Answer

Amazon Athena

Answer

Amazon RDS for MySQL

Question 6

A gaming company needs a database to store player session data that is ephemeral and requires sub-millisecond latency. The data can be lost on failure without impact. Which service is best?

Accepted Answer

Amazon ElastiCache for Redis. Amazon ElastiCache for Redis is the best choice because it provides an in-memory data store with sub-millisecond latency, ideal for ephemeral player session data that can be lost on failure. Redis supports data structures like strings and hashes with TTL (time-to-live) expiration, perfectly matching the transient, low-latency requirement without needing durability.

Answer

Amazon DynamoDB

Answer

Amazon RDS for PostgreSQL

Answer

Amazon S3

Question 7

A company is designing a database for a mobile application that requires offline synchronization. Users should be able to read and write data while offline, and changes should sync when connectivity is restored. Which AWS service supports this pattern?

Accepted Answer

AWS AppSync with Amazon DynamoDB. AWS AppSync with Amazon DynamoDB is correct because AppSync provides managed GraphQL APIs that support offline data synchronization via its client SDKs. When a mobile app is offline, mutations are queued locally and automatically replayed against DynamoDB once connectivity is restored, using a conflict resolution mechanism (e.g., last-writer-wins or custom resolvers) to merge changes.

Answer

Amazon RDS Proxy

Answer

Amazon S3 Transfer Acceleration

Answer

Amazon Cognito

Question 8

Which TWO database services are most suitable for workloads that require ACID transactions?

Accepted Answer

Amazon Aurora. Amazon Aurora is correct because it is a MySQL- and PostgreSQL-compatible relational database engine that provides full ACID (Atomicity, Consistency, Isolation, Durability) transaction support, including multi-statement transactions with commit and rollback. Aurora uses a distributed, fault-tolerant storage subsystem that replicates data across three Availability Zones, ensuring durability and consistency for transactional workloads.

Answer

Amazon Neptune

Answer

Amazon Timestream

Answer

Amazon DynamoDB

Question 9

Which THREE factors should be considered when designing a database for a high-traffic web application that requires low-latency reads and writes?

Accepted Answer

Caching layer. A caching layer (e.g., Amazon ElastiCache for Redis or Memcached) reduces read latency by serving frequently accessed data from in-memory stores, offloading the primary database. For high-traffic web applications, this minimizes disk I/O and improves response times for both reads and writes when combined with write-through or write-behind strategies.

Answer

Strict normalization

Answer

Denormalization of data

Question 10

Which TWO AWS services can be used to implement a serverless database architecture for variable workloads?

Accepted Answer

Amazon Aurora Serverless v2. Amazon Aurora Serverless v2 is correct because it automatically scales database capacity up or down based on application demand, providing a serverless architecture for variable workloads without the need to manage database instances. Amazon DynamoDB is correct because it is a fully managed NoSQL serverless database that automatically scales throughput and storage to handle variable workloads, requiring no server provisioning or management.

Answer

Amazon Redshift

Answer

Amazon RDS Proxy

Answer

Amazon ElastiCache

Question 11

A company is designing a database for an e-commerce platform that requires high availability and automatic failover with minimal downtime. The application performs both OLTP and read-heavy analytics. Which AWS database service should be used?

Accepted Answer

Amazon Aurora. Amazon Aurora is the correct choice because it combines the high availability and automatic failover of a relational database with the performance needed for both OLTP and read-heavy analytics. Aurora provides six-way replication across three Availability Zones, automatic failover in under 30 seconds, and supports up to 15 low-latency read replicas that can offload analytics queries without impacting write performance.

Answer

Amazon DynamoDB

Answer

Amazon RDS for MySQL

Answer

Amazon Redshift

Question 12

A startup is building a real-time leaderboard for a gaming application. The data is highly dynamic with frequent updates and requires single-digit millisecond latency. Which database is most suitable?

Accepted Answer

Amazon DynamoDB. Amazon DynamoDB is the most suitable choice because it is a fully managed NoSQL key-value and document database that delivers single-digit millisecond latency at any scale, making it ideal for real-time leaderboards with high-frequency updates. Its DAX (DynamoDB Accelerator) caching layer can further reduce read latency to microseconds, while its auto-scaling and on-demand capacity modes handle the highly dynamic workload without downtime.

Answer

Amazon Neptune

Answer

Amazon Redshift

Answer

Amazon RDS for PostgreSQL

Question 13

A company needs to migrate an on-premises Oracle database to AWS with minimal changes to the application code. The application uses complex stored procedures and has high availability requirements. Which database service should be used?

Accepted Answer

Amazon RDS for Oracle. Amazon RDS for Oracle is the correct choice because it provides native Oracle compatibility, supporting complex stored procedures, PL/SQL, and existing application code with minimal changes. It also offers Multi-AZ deployments for high availability, meeting the requirement without requiring a complete rewrite.

Answer

Amazon DynamoDB

Answer

Amazon Redshift

Answer

Amazon Aurora PostgreSQL

Question 14

A company is building a document management system where each document can have multiple attributes (tags) that need to be queried efficiently. The workload is write-heavy with occasional reads. Which database is best suited?

Accepted Answer

Amazon DynamoDB. Amazon DynamoDB is the best choice for a write-heavy, document management system with tag-based queries because it is a fully managed NoSQL key-value and document database that delivers single-digit millisecond performance at any scale. Its flexible schema allows each document to have multiple attributes (tags) without predefined schemas, and its secondary indexes (LSI/GSI) enable efficient querying on those tags. DynamoDB's auto-scaling and provisioned throughput are designed to handle high write volumes, while occasional reads benefit from its consistent low-latency access.

Answer

Amazon QLDB

Answer

Amazon ElastiCache for Redis

Answer

Amazon RDS for MySQL

Question 15

A company is designing a multi-region active-active application that requires low-latency reads and writes across regions. The database must support conflict resolution. Which database should be used?

Accepted Answer

Amazon DynamoDB Global Tables. Amazon DynamoDB Global Tables is the correct choice because it provides a fully managed, multi-region, multi-active database that replicates data across regions with eventual consistency, supporting low-latency reads and writes. It includes built-in conflict resolution using a last-writer-wins (LWW) mechanism based on timestamps, which meets the requirement for conflict resolution in an active-active architecture.

Answer

Amazon RDS Multi-AZ

Answer

Amazon Redshift

Answer

Amazon Aurora Global Database