Databases Flashcards
Which of the following does Amazon Relational Database Service (Amazon RDS) manage on your behalf? (Select THREE.)
A. Database settings
B. Database software installation and patching
C. Query optimization
D. Hardware provisioning
E. Backups
Database software installation and patching
Hardware provisioning
Backups
Which AWS database service is best suited for managing highly connected datasets? A. Amazon Aurora B. Amazon Neptune C. Amazon DynamoDB D. Amazon Redshift
Neptune (graph database)
You are designing an e-commerce web application that will scale to potentially hundreds of thousands of concurrent users. Which database technology is best suited to hold the session state for large numbers of concurrent users?
A. Relational database by using Amazon Relational Database Service (Amazon RDS)
B. NoSQL database table by using Amazon DynamoDB
C. Data warehouse by using Amazon Redshift
D. MySQL on Amazon EC2
NoSQL database table by using DynamoDB
How many read capacity units (RCUs) do you need to support 25 strongly consistent reads per seconds of 15 KB? A. 100 RCUs B. 25 RCUs C. 10 RCUs D. 15 RCUs
100 RCUs
1 RCU = 1 strong consistent read of 4 KB
15 KB ~ 4 x 4 KB/strong consistent read
4 x 25 = 100 RCUs
How many read capacity units (RCUs) do you need to support 25 eventually consistent reads per seconds of 15 KB? A. 10 RCUs B. 25 RCUs C. 50 RCUs D. 15 RCUs
50 RCUs
1 RCU = 2 eventual consistent reads of 4 KB
15 KB = 4 reads
25 x 4 / 2 = 50 RCUs
How many write capacity units (WCUs) are needed to support 100 writers per second of 512 bytes? A. 129 WCUs B. 25 WCUs C. 10 WCUs D. 100 WCUs
100 WCUs
1 WCU = 1 write of 1 KB
512 bytes write uses 1 chunk of 1 KB
100 writes/s = 100 WCUs
Your company is using Amazon DynamoDB, and they would like to implement a write-through caching mechanism. They would like to get everything up and running in only a few short weeks. Additionally, your company would like to refrain from managing any additional servers. You are the lead developer on the project; what should you recommend?
A. Build your own custom caching application.
B. Implement Amazon DynamoDB Accelerator (DAX).
C. Run Redis on Amazon EC2.
D. Run Memcached on Amazon EC2.
Implement DynamoDB Accelerator (DAX)
it supports write-through cache with little code change
Your company would like to implement a highly available caching solution for its SQL database running on Amazon RDS. Currently, all of its services are running in the AWS Cloud. As their lead developer, what should you recommend?
A. Implement your own caching solution on-premises.
B. Implement Amazon ElastiCache for Redis.
C. Implement Amazon ElastiCache for Memcached.
D. Implement Amazon DynamoDB Accelerator (DAX).
ElastiCache for Redis
Notes:
ElastiCache for Memcached does not support high-availability
DAX is for DynamoDB, not RDS
A company is looking to run analytical queries and would like to implement a data warehouse. It estimates that it has roughly 300 TB worth of data, which is expected to double in the next three years. Which AWS service should you recommend?
A. Relational database by using Amazon Relational Database Service (Amazon RDS)
B. NoSQL database table by using Amazon DynamoDB
C. Data warehouse by using Amazon Redshift
D. Amazon ElastiCache for Redis
Redshift
A company is experiencing an issue with Amazon DynamoDB whereby the data is taking longer than expected to return from a query. You are tasked with investigating the problem. After looking at the application code, you realize that a Scan operation is being called for a large DynamoDB table. What should you do or recommend?
A. Implement a query instead of a scan, if possible, as queries are more efficient than a scan.
B. Do nothing; the problem should go away on its own.
C. Implement a strongly consistent read.
D. Increase the write capacity units (WCUs).
Implement a query instead of scan
