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

Ans D: This is the best solution. By using an SQS FIFO queue, you can store customer data reliably even when the database is temporarily unavailable. The Lambda function can immediately write the data to the queue when the database is not available. A second Lambda function can then poll the queue and process the customer data when the database becomes available again. This ensures that no data is lost, and processing happens in an orderly manner.

Scenario describes 1 DB and when it's unavailable due to an upgrade. Best solution is to queue incoming data until DB is available.

Initially I voted A. But thats wrong for one reason. RDS proxy wont help if there is no more than 1 database, but again - if there is just one database, the application is down during the downtime anyways, there is nothing that can be done. However, a SQS queue is a better option for the reason that the messages persist until marked processed. That guarantee alone is good enough to make D a better choice. But jeez! talk about trickery!! deceptively misleading!

D does not work. because the during db upgrade the connection is disrupted for a while during which the request in SQS will be consumed and lost

Google does aws aurora db proxy help db upgrade, proxy will cache transaction,

decouple the application so that we can save the failed transactions and then pull after the upgrades complete, so D should be the correct answer (SQS Queue)

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.