Exam AWS Certified Solutions Architect - Associate SAA-C03 topic 1 question 87 discussion

https://aws.amazon.com/rds/proxy/ RDS Proxy minimizes application disruption from outages affecting the availability of your database by automatically connecting to a new database instance while preserving application connections. When failovers occur, RDS Proxy routes requests directly to the new database instance. This reduces failover times for Aurora and RDS databases by up to 66%.

The answer is D. RDS Proxy doesn't support Aurora DBs. See limitations at: https://docs.aws.amazon.com/AmazonRDS/latest/AuroraUserGuide/rds-proxy.html

this is not failover situation so no need to use rds proxy. i dont remember rds proxy to hold data incase for db unavailability

A for sure

It's not a failover situation, it's just temporarily unavailable.

Ans D - as excellently explained by SaurabhTiwari1 (9 mth ago) "The original question was about handling a situation where the database is unavailable due to an upgrade, not a failover situation. During a database upgrade, the database instance is not available, and RDS Proxy would not be able to connect to a new database instance because there isn’t one." In this specific scenario, using Amazon SQS as described in option D provides a buffer for the incoming data during the period when the database is unavailable. This ensures that no data is lost, and it can be written to the database once the upgrade is complete

A is incorrect

the answer is D: This solution ensures that customer data is not lost during database upgrades. The data is stored in the FIFO queue until the database is available again. The new Lambda function can then process the data from the queue and store it in the database. This design provides a buffer for the customer data and decouples the data ingestion from the data processing, increasing the resilience of the system during database upgrades.

By using Amazon RDS Proxy, you can allow your applications to pool and share database connections to improve their ability to scale. RDS Proxy makes applications more resilient to database failures by automatically connecting to a standby DB instance while preserving application connections. Using RDS Proxy, you can handle unpredictable surges in database traffic. Otherwise, these surges might cause issues due to oversubscribing connections or new connections being created at a fast rate.

D is the correct answer because it offers storage for the data while the database is updating, using SQS is better than using RDS proxy, because SQS is an independent service and it decouples the system, while RDS proxy might also face some trouble connecting to the database while it's updating.

My reasoning for selecting D and not A is because while RDS proxy can decouple the lambda->proxy and proxy-db connections, it cannot hold that beyond the lifetime of the lambda. If the DB upgrade lasts more than say 15 mins, the lambda will timeout and the data will be lost forever. The only way to be sure is to use an SQS queue with a retention time that is reasonably longer than the upgrade time, so if the lambda times out, the data will remain in the queue until it is successfully inserted into the DB later and then removed from the queue.

RDS proxy can improve application availability in such a situation by waiting for the new database instance to be functional and maintaining any requests received from the application during this time. The end result is that the application is more resilient to issues with the underlying database. This will enable solution to hold data till the time DB comes back to normal.

d is the answer

Originally I felt option A is correct but looks like D is correct since even though rds proxy can support aurora db and minor db upgrades, the question mentions the db upgrades which could be major or minor in which case rds proxy may not be right.

Amazon SQS FIFO Queue: Amazon SQS FIFO (First-In-First-Out) queues provide exactly-once processing, ensuring that messages are processed in the order they are received and are not duplicated. This ensures the reliability of message delivery, crucial for preserving customer data. Lambda Function to Process Queue: Create a new Lambda function that regularly polls the SQS FIFO queue for messages containing customer data. Lambda can be configured to trigger based on a schedule or on demand. This function will retrieve messages from the queue and process them, storing the customer data in the database.

RDS proxy is correct Many applications, including those built on modern serverless architectures, can have a large number of open connections to the database server and may open and close database connections at a high rate, exhausting database memory and compute resources. Amazon RDS Proxy allows applications to pool and share connections established with the database, improving database efficiency and application scalability. With RDS Proxy, failover times for Aurora and RDS databases are reduced by up to 66% and database credentials, authentication, and access can be managed through integration with AWS Secrets Manager and AWS Identity and Access Management (IAM).

This option introduces a decoupling mechanism using SQS, allowing the Lambda functions to push customer data to a queue during database upgrades. Another Lambda function can then process the queue and store the customer data in the database. This helps to ensure that customer data is not lost during database upgrades, providing a reliable and asynchronous approach to handle such scenarios.