DBS-C01 Workload-Specific Database Design Practice Test 23 — 15 Questions

Question 1

A company is designing a relational database for an e-commerce application that requires high availability and automated failover across AWS Regions. Which AWS database service should they use?

Accepted Answer

Amazon Aurora Global Database. Amazon Aurora Global Database provides cross-Region replication and automated failover, meeting the high availability requirements. Option A (DynamoDB) is NoSQL, not relational. Option B (RDS Multi-AZ) is single-Region. Option D (Redshift) is a data warehouse, not for OLTP.

Answer

Amazon DynamoDB Global Tables

Answer

Amazon RDS with Multi-AZ deployment

Answer

Amazon Redshift with cross-Region snapshot copy

Question 2

A financial services company needs to enforce row-level security on a MySQL database hosted on Amazon RDS. They want to restrict access so that each application user can only see their own data. Which approach should they take?

Accepted Answer

Use a MySQL proxy that injects session context variables and enable row-level security in the application queries. Using MySQL proxy with session context variables allows row-level filtering based on user identity. Option A (IAM policy) doesn't apply to database rows. Option B (views per user) is not scalable. Option D (VPC endpoints) doesn't control row access.

Answer

Place each user's data in a separate database and use VPC endpoints to isolate access

Answer

Create separate database views for each user

Answer

Use IAM database authentication and define fine-grained access policies

Question 3

A company is migrating an on-premises Oracle OLTP workload to AWS. The database has complex stored procedures and requires minimal code changes. Which AWS database service is the most suitable target?

Accepted Answer

Amazon RDS for Oracle. Amazon RDS for Oracle allows minimal code changes as it is compatible with Oracle. Option B (Aurora PostgreSQL) would require rewriting procedures. Option C (DynamoDB) is NoSQL. Option D (Redshift) is for analytics.

Answer

Amazon Redshift

Answer

Amazon DynamoDB

Answer

Amazon Aurora PostgreSQL

Question 4

A company runs a critical PostgreSQL database on Amazon RDS and needs to implement point-in-time recovery (PITR) with a recovery window of the last 35 days. Currently, automated backups are set to retain for 35 days. The database size is 500 GB. What additional configuration is required?

Accepted Answer

No additional configuration is required; automated backups enable PITR. Automated backups in RDS by default support PITR within the retention period. No additional configuration is needed. Option A (manual snapshots) is not required. Option B (Multi-AZ) doesn't affect PITR. Option D (log shipping) is not a separate feature.

Answer

Enable manual snapshots every hour

Answer

Set up a replication slot and stream transaction logs to S3

Answer

Enable Multi-AZ deployment

Question 5

A social media startup is selecting a database for user profiles with a flexible schema and high write throughput. The application is built on Node.js and requires low-latency access. Which database should they choose?

Accepted Answer

Amazon DynamoDB. Amazon DynamoDB is a NoSQL key-value and document database that offers flexible schema and high throughput with low latency. Option A (Aurora) is relational. Option B (RDS MySQL) is relational. Option D (ElastiCache) is a cache, not a primary database.

Answer

Amazon Aurora

Answer

Amazon ElastiCache for Redis

Answer

Amazon RDS for MySQL

Question 6

A company needs to run complex analytical queries on structured data in Amazon S3 without loading data into a database. The queries must execute quickly and support standard SQL. Which service should they use?

Accepted Answer

Amazon Athena. Amazon Athena is an interactive query service that analyzes data in S3 using standard SQL. Option B (Redshift Spectrum) also works but requires a Redshift cluster. Option C (Glue ETL) is for ETL jobs. Option D (QuickSight) is a BI tool.

Answer

Amazon QuickSight

Answer

AWS Glue ETL jobs

Answer

Amazon Redshift Spectrum

Question 7

A company is designing a global application that requires a database with multi-master writes across multiple AWS Regions with sub-second conflict resolution. Which AWS database service should they choose?

Accepted Answer

Amazon DynamoDB Global Tables. Amazon DynamoDB Global Tables provides multi-Region, multi-master replication with eventual consistency and sub-second conflict resolution. Option A (Aurora Global Database) has a single primary. Option C (RDS Multi-AZ) is single-Region. Option D (ElastiCache) is a cache.

Answer

Amazon ElastiCache for Redis Global Datastore

Answer

Amazon RDS with Multi-AZ

Answer

Amazon Aurora Global Database

Question 8

A company needs to store JSON documents that require complex querying on nested attributes. The database must support ACID transactions and be fully managed. Which service should they use?

Accepted Answer

Amazon Aurora MySQL. Amazon Aurora MySQL-Compatible Edition supports JSON data type and ACID transactions. Option B (DynamoDB) is NoSQL but does not support complex nested queries natively. Option C (DocumentDB) is MongoDB-compatible but not ACID. Option D (Neptune) is graph database.

Answer

Amazon DocumentDB (with MongoDB compatibility)

Answer

Amazon DynamoDB

Answer

Amazon Neptune

Question 9

A company has an Amazon RDS for PostgreSQL instance that is running out of storage. The database is 2 TB in size and growing at 10 GB per day. They need a solution that allows automatic storage scaling with minimal downtime. What should they do?

Accepted Answer

Enable Storage Auto Scaling. Amazon RDS Storage Auto Scaling automatically increases storage when needed, with no downtime. Option A (manual snapshot) requires downtime. Option B (read replica) doesn't address storage. Option D (reserved instances) is a billing option.

Answer

Purchase reserved instances for cost savings

Answer

Create a read replica and promote it

Answer

Take a manual snapshot and restore to a larger instance

Question 10

Which TWO database services are suitable for storing time-series data with high ingestion rates? (Select TWO.)

Accepted Answer

Amazon Timestream. Amazon Timestream is purpose-built for time-series. DynamoDB with TTL can be used for time-series with efficient expiration. Options C, D, E are not optimal for high ingestion time-series.

Answer

Amazon RDS for MySQL

Answer

Amazon ElastiCache for Memcached

Answer

Amazon Redshift

Question 11

Which THREE factors should be considered when choosing between Amazon DynamoDB and Amazon Aurora for a new application? (Select THREE.)

Accepted Answer

Access patterns (key-value vs relational queries). Access pattern (key-value vs relational), transaction support (Aurora supports complex transactions), and scalability model (DynamoDB scales horizontally) are key. Data size and cost are not primary differentiators.

Answer

Cost per GB of storage

Answer

Maximum data size per table

Question 12

Which TWO AWS services can be used to cache database query results to improve read performance? (Select TWO.)

Accepted Answer

Amazon ElastiCache for Redis. Amazon ElastiCache for Redis and Amazon ElastiCache for Memcached are in-memory caching services. DAX is for DynamoDB only. RDS does not cache. CloudFront is CDN.

Answer

Amazon DynamoDB Accelerator (DAX)

Answer

Amazon CloudFront

Answer

Amazon RDS read replica

Question 13

A company is designing a database for an IoT application that ingests millions of sensor readings per second. Each reading is a small JSON document (less than 1 KB) and must be stored with low latency. Queries are primarily by device ID and timestamp range. The team expects to rarely update or delete old data. Which AWS database solution is MOST cost-effective and performant?

Accepted Answer

Amazon DynamoDB with a composite primary key (device_id, timestamp). Amazon DynamoDB is a NoSQL key-value and document database that provides single-digit millisecond latency at any scale. It is ideal for high-throughput ingestion of small items with simple access patterns (device ID + timestamp). Option A is wrong because Amazon RDS for MySQL is relational and would require scaling a single master, leading to bottlenecks. Option C is wrong because Amazon Redshift is a data warehouse optimized for analytics, not real-time ingestion. Option D is wrong because Amazon S3 is an object store with higher latency for individual small writes.

Answer

Amazon S3 with a partition prefix of device_id/timestamp/

Answer

Amazon Redshift with distribution key on device_id

Answer

Amazon RDS for MySQL with multiple read replicas

Question 14

A financial services company runs a critical PostgreSQL database on Amazon RDS. The database stores transaction records and requires point-in-time recovery (PITR) with a recovery window of 35 days. The database size is 500 GB and grows at 10 GB per day. The team wants to minimize storage costs while meeting the recovery SLA. Which backup strategy should they use?

Accepted Answer

Enable automated backups with a retention period of 35 days. Amazon RDS automated backups provide PITR within the retention period (up to 35 days). They store transaction logs continuously, allowing recovery to any second within the window. Option B is wrong because manual snapshots every hour would be expensive and cumbersome. Option C is wrong because cross-region snapshots do not provide PITR and are for disaster recovery. Option D is wrong because disabling automated backups and using pg_dump would lose ability to recover to a specific point in time.

Answer

Take manual snapshots every hour and retain for 35 days

Answer

Disable automated backups and use pg_dump to S3 daily

Answer

Use AWS Backup to copy snapshots to another region daily

Question 15

A startup is building a social media application that requires storing user profiles, posts, comments, and likes. The workload has variable traffic, with spikes after marketing campaigns. The team expects to run complex JOIN queries to generate a user's feed. Which AWS database service is MOST suitable for this relational workload?

Accepted Answer

Amazon RDS for PostgreSQL. Amazon RDS provides managed relational databases (MySQL, PostgreSQL) that support complex JOINs and can be scaled vertically or with read replicas. Option B is wrong because DynamoDB is NoSQL and does not natively support JOINs. Option C is wrong because ElastiCache is an in-memory cache, not a primary database. Option D is wrong because Neptune is a graph database, which is overkill and not optimized for typical relational queries.

Answer

Amazon Neptune

Answer

Amazon DynamoDB with global secondary indexes

Answer

Amazon ElastiCache for Redis