Task 3: Use Data Stores in Application Development DVA-C02 Practice Questions (Page 1)

Questions 1–5

1. 1foundation · easy

   What is the primary benefit of using Amazon ElastiCache in front of a database?

   • AIt encrypts all data stored in the database
   • BIt provides a relational database engine for complex queries
   • CIt reduces database load by serving frequently accessed data from an in-memory cache
   • DIt automatically backs up the database to S3
   Reveal Solution Discussion Select an answer first
2. 2expert · hard

   A developer is troubleshooting a slow DynamoDB query. The table has a composite primary key (`user_id`, `order_id`) and a GSI on `status`. The query is: `SELECT * FROM orders WHERE status = 'PENDING'`. The developer notices that the query returns results slowly and consumes a lot of read capacity. The table has millions of items, but only a few thousand are in 'PENDING' status. What is the most likely cause of the poor performance?

   • AThe GSI is not projected with all the attributes needed, causing the query to fetch items from the base table.
   • BThe query is performing a Scan on the base table instead of using the GSI.
   • CThe table has too many partitions, causing the query to be slow.
   • DThe query is using the GSI on `status`, which is efficient because it only reads items with that status.
   Reveal Solution Discussion Select an answer first
4. 3foundation · easy

   What is the purpose of setting a DynamoDB table to use on-demand capacity mode?

   • ATo reduce storage costs by compressing data
   • BTo automatically scale read and write capacity based on traffic
   • CTo enable cross-region replication
   • DTo provide a fixed amount of capacity that never changes
   Reveal Solution Discussion Select an answer first
5. 4foundation · easy

   An application needs to store and query time-series data with high write throughput and efficient range queries on timestamps. Which AWS service is most appropriate?

   • AAmazon DynamoDB
   • BAmazon RDS
   • CAmazon Timestream
   • DAmazon OpenSearch Service
   Reveal Solution Discussion Select an answer first
6. 5foundation · easy

   What is the role of a sort key in a DynamoDB primary key?

   • AIt uniquely identifies each item in the table
   • BIt distributes data evenly across partitions
   • CIt allows items with the same partition key to be stored and retrieved in sorted order
   • DIt is required for all DynamoDB tables
   Reveal Solution Discussion Select an answer first