DBS-C01 Workload-Specific Database Design Practice Test 5 — 15 Questions

Question 1

A company uses Amazon DynamoDB for a session management workload. The access pattern is random and requires single-digit millisecond latency. The table has a read capacity of 5000 RCU. During peak hours, read requests occasionally exceed this capacity, causing throttling. Which design change is most appropriate to handle traffic spikes?

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

Accepted Answer

Enable DynamoDB auto scaling for reads.. DynamoDB auto scaling allows the table to dynamically adjust its provisioned read capacity (RCU) in response to traffic spikes, preventing throttling while maintaining single-digit millisecond latency. This is the most appropriate design change for a session management workload with random access patterns, as it handles occasional bursts without requiring manual intervention or architectural changes.

Answer

Switch to DynamoDB on-demand mode.

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Add a global secondary index with different partition key.

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Add a DAX cluster to cache read requests.

Question 2

A company is designing a document database on Amazon DocumentDB for a content management system. Which TWO design practices improve query performance and reduce costs?

Accepted Answer

Use appropriate indexes to support common query patterns.. In Amazon DocumentDB, only Option E (Use appropriate indexes to support common query patterns) is correct. Sharding (Option A) is not supported by DocumentDB. Options B, C, and D are incorrect because they would degrade performance or increase costs. Note: The question asks for two, but only one option is correct.

Answer

Shard data based on access patterns to distribute load.

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Design documents to avoid joins by frequently using $lookup.

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Avoid denormalization to maintain strict normal forms.

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Store all documents in a single collection without indexes to reduce overhead.

Question 3

A company needs to choose a database for a real-time analytics workload that requires sub-second query latency on streaming data. Which TWO AWS services are most suitable?

Accepted Answer

Amazon Redshift with streaming ingestion from Kinesis.. Amazon Timestream is purpose-built for time-series data and provides sub-second query latency on streaming data via its dedicated query engine and automatic tiering between in-memory and magnetic stores. Amazon Redshift with streaming ingestion from Kinesis enables real-time analytics by directly consuming Kinesis data streams into Redshift materialized views, allowing sub-second queries on fresh data without batch loading.

Answer

Amazon Neptune.

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Amazon RDS for PostgreSQL with materialized views.

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Amazon DynamoDB Accelerator (DAX).

Question 4

A company is migrating a large Oracle data warehouse to Amazon Redshift. Which THREE design considerations are important for performance optimization?

Accepted Answer

Choose appropriate distribution styles (KEY, ALL, EVEN).. Distribution styles (KEY, ALL, EVEN) control how data is distributed across compute nodes in Amazon Redshift. Choosing the right distribution style minimizes data movement during joins and aggregations, which is critical for performance in a large data warehouse migration from Oracle. For example, using KEY distribution on a frequently joined column keeps related rows on the same node, reducing network traffic.

Answer

Enable cross-Region replication for data locality.

Answer

Use row-based storage for fact tables.

Question 5

A media company is storing large video files (up to 10 GB each) in Amazon S3 and needs to maintain metadata about each file, including title, duration, and upload timestamp. The workload involves frequent writes (1000+ per second) and occasional read queries by title. Which database is best suited for this metadata store?

Accepted Answer

Amazon DynamoDB. Amazon DynamoDB is the best choice because it supports single-digit millisecond latency at any scale, handles over 1000 writes per second with auto-scaling, and can efficiently serve occasional read queries by title using a global secondary index (GSI) on the title attribute. Its fully managed, serverless nature eliminates operational overhead for high-throughput metadata storage.

Answer

Amazon Neptune

Answer

Amazon RDS for MySQL

Answer

Amazon ElastiCache for Memcached

Question 6

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 7

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 8

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

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Amazon RDS for MySQL

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Amazon ElastiCache for Redis

Question 9

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

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Amazon RDS for PostgreSQL

Question 10

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 11

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 12

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 13

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 14

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 15

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