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Exam AWS Certified Solutions Architect - Associate SAA-C02 topic 1 question 362 discussion

Exam question from Amazon's AWS Certified Solutions Architect - Associate SAA-C02
Question #: 362
Topic #: 1
[All AWS Certified Solutions Architect - Associate SAA-C02 Questions]

A company is using Amazon DynamoDB with provisioned throughput for the database tier of its ecommerce website. During flash sales, customers experience periods of time when the database cannot handle the high number of transactions taking place. This causes the company to lose transactions. During normal periods, the database performs appropriately.
Which solution solves the performance problem the company faces?

  • A. Switch DynamoDB to on-demand mode during flash sales.
  • B. Implement DynamoDB Accelerator for fast in memory performance.
  • C. Use Amazon Kinesis to queue transactions for processing to DynamoDB.
  • D. Use Amazon Simple Queue Service (Amazon SQS) to queue transactions to DynamoDB.
Show Suggested Answer Hide Answer
Suggested Answer: A 🗳️
by dmscountera at March 11, 2021, 5:39 p.m.
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waqas
Highly Voted 3 years, 7 months ago
A to me....
upvoted 41 times
Goozian
3 years, 6 months ago
If you need more than double your previous peak on table, DynamoDB automatically allocates more capacity as your traffic volume increases to help ensure that your workload does not experience throttling
upvoted 2 times
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waqas
3 years, 7 months ago
Transaction are both for WRITE as well for GET types.....but here in question it is not clearly mentioned that only requirement is for read else suits best....as its the Use case for DAX if reads are involved only.
upvoted 3 times
waqas
3 years, 7 months ago
Igonore my above comments. Answer is A. Transaction are both for WRITE as well for GET types.....but here in question it is not clearly mentioned that only requirement is for read as DAX was best in that case....because its the special Use case for DAX if reads are involved only in the question...
upvoted 2 times
noahsark
3 years, 6 months ago
DAX is also a write-through cache because it caches (or updates) items with PutItem, UpdateItem, DeleteItem, and BatchWriteItem API calls as the data is written to or updated in DynamoDB. https://aws.amazon.com/blogs/database/amazon-dynamodb-accelerator-dax-a-read-throughwrite-through-cache-for-dynamodb/
upvoted 2 times
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noahsark
3 years, 6 months ago
B- Applications that read a small number of items more frequently than others. For example, consider an ecommerce system that has a one-day sale on a popular product. During the sale, demand for that product (and its data in DynamoDB) would sharply increase, compared to all of the other products. To mitigate the impacts of a "hot" key and a non-uniform traffic distribution, you could offload the read activity to a DAX cache until the one-day sale is over. https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/DAX.html
upvoted 12 times
robertomartinez
3 years, 6 months ago
Most important issue with DAX IMHO is that it does not works with transaction because DAX does not support strong consistency, it would be a nogo for such a transactionnal case because it would just be useless :) and forward everything to dynamo with 0% cache hit . Check https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/DAX.consistency.html#DAX.consistency.strongly-consistent-reads
upvoted 3 times
RandomLettersAndNumbers
3 years, 6 months ago
Not sure why everyone considers "transaction" in technical perspective. Question says: "company is loosing transactions". I would consider that as an commercial thing. That is selling an item. In such case you can loose transaction because you are unable to present something to the customer. That means that reads are failing. And answer B is perfectly fine. Another argument is that this exam actually is an commercial for AWS products, they just want to make you know various types of their products. So again, B is perfectly fine as you learn about other AWS product.
upvoted 3 times
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cnmc
3 years, 6 months ago
Sure this link deals with a flash sale and Dynamodb, but you stopped reading right there... In the link, DAX helps to mitigate the effect of high READ traffic. You’re doing a flash sale on a product, people will view that product’s page a lot, so you put it in a cache (DAX), sure makes sense. But this questions specifically asked for another problem - they are LOSING TRANSACTIONS. Think about it, how does a cache help you with transaction loss? They lose transaction because the database itself didn’t have the capacity to handle all those demands. A is the right answer
upvoted 48 times
kdhondge
3 years, 5 months ago
Great explanation. A make sense
upvoted 1 times
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VijiTu
2 years, 11 months ago
DAX support both read and Write. But still appreciate your detailed explaination
upvoted 1 times
ChiefArch
2 years, 9 months ago
Incorrect and it is explicitly called out that DAX is not for write intensive use cases. https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/DAX.html
upvoted 1 times
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occupatissimo
Highly Voted 3 years, 7 months ago
B is out because it's used in case of latency for read operation C is out because kinesis ingest and not queue D is out because SQS need something that poll it and dynamo doesn’t do it (except for stream but it isn’t mentioned) A remain and is ok because on-demand is right used to unlock any capacity planning provided with provisioned mode
upvoted 20 times
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BECAUSE
Most Recent 1 year, 11 months ago
Selected Answer: A
A is the answer
upvoted 1 times
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SkyZeroZx
2 years ago
Selected Answer: A
A it is indeed
upvoted 1 times
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_charissi
2 years, 7 months ago
Selected Answer: A
B is for reads not writes
upvoted 1 times
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miles3719
2 years, 8 months ago
Selected Answer: A
A it is indeed
upvoted 1 times
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Prakashn0509
2 years, 8 months ago
Correct Answer is A, Dynamo DB On-Demand mode is used for unpredictable workloads.
upvoted 1 times
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queen101
2 years, 9 months ago
DynamoDB with On-Demand mode executed.
upvoted 2 times
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cloud_collector
2 years, 9 months ago
About the word of "transactions" , find out this descriptions as below: DynamoDB transactions provide developers atomicity, consistency, isolation, and durability (ACID) across one or more tables within a single AWS account and region. You can use transactions when building applications that require coordinated inserts, deletes, or updates to multiple items as part of a single logical business operation. https://aws.amazon.com/blogs/aws/new-amazon-dynamodb-transactions/ It should include the "read & write".
upvoted 1 times
cloud_collector
2 years, 9 months ago
Continue... DAX is not ideal for the following types of applications: Applications that are write-intensive, or that do not perform much read activity. https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/DAX.html I think the "DynamoDB to on-demand mode" is better on this quesion.
upvoted 1 times
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marklovesaws143
2 years, 9 months ago
Selected Answer: A
AAAAAAAAAAAAAAAAA
upvoted 1 times
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slcheng
2 years, 10 months ago
DB operation normal during no flash sale. A - Amazon DynamoDB on-demand is a flexible billing option capable of serving thousands of requests per second without capacity planning. For on-demand mode tables, you don't need to specify how much read and write throughput you expect your application to perform. DynamoDB tables using on-demand capacity mode automatically adapt to your application’s traffic volume. On-demand capacity mode instantly accommodates up to double the previous peak traffic on a table
upvoted 3 times
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Ashu_0007
2 years, 11 months ago
Selected Answer: A
DAX for readonly scenarios but for transactions you need on demand capacity
upvoted 3 times
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user0001
3 years, 1 month ago
A: since the time of the spike is known, the problem is with write and not read
upvoted 1 times
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Venki_dev
3 years, 1 month ago
Selected Answer: A
Answer is A DynamoDB on-demand is useful if your application traffic is difficult to predict and control, your workload has large spikes of short duration, or if your average table utilization is well below the peak. https://aws.amazon.com/blogs/aws/amazon-dynamodb-on-demand-no-capacity-planning-and-pay-per-request-pricing/
upvoted 3 times
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pandasmarted
3 years, 2 months ago
Selected Answer: B
Isn't it be? Read/write improvement. Or is it A because it's a spot increase and not used during non-flash sales? https://aws.amazon.com/blogs/database/amazon-dynamodb-accelerator-dax-a-read-throughwrite-through-cache-for-dynamodb/
upvoted 1 times
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AhmedKhaled86
3 years, 2 months ago
Selected Answer: A
A for sure
upvoted 1 times
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HazimSalim
3 years, 3 months ago
I think A
upvoted 1 times
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