CODEWITHSUNDEEP
amazon-dynamodb
Distraction Arrestor
Distraction Arrestor

Reputation: 301

AWS DynamoDB: read/write units estimation issue

I am creating an online crowd driven game. I expect the read/write requests to fluctuate (like, 50,50,50,1500,50,50,50)every second and I need to process all 100% requests with strong consistency.

I am planning to go with AWS's DynamoDB from GAE datastore for its strong consistency. I have the below doubts which I could not get clear answers in other discussions.

1. If the item size for a write action is just 4B, Will that be rounded to a 1KB and consume a write unit?

2. Financially it is not wise to set the Provisioned Throughput Capacity around the expected peak value. Alarms can warn us. But in the case of sudden rise, the requests could be throttled at the time we receive alarm. Is DynamoDB really designed to handle highly fluctuating read/write?

3. I read about Dynamc DynamoDB to update the read/write throughput capacity for us, When we add some read/write units, How long it will take to allocate them? If it takes too long, Whats the use of increasing the bar after the tide hits?

Google app engine bills just for the number of requests happen in that month. If I can make AWS work like, "Whatever the request count could be, I will expand and contract myself and charge you only for the used read/write units", I will go for AWS.

Please advise. Dont hesitate if I am not being clear at parts.

Thanks, Karthick.

Upvotes: 1

Views: 357

Answers (1)

mkobit
mkobit

Reputation: 47249

  1. Yes. Item sizes are rounded up and the throughput is used. From the Provisioned Throughput in Amazon DynamoDB documentation:

    The total number of read operations necessary is the item size, rounded up to the next multiple of 4 KB, divided by 4 KB.

  2. It can handle some bursting, but it is generally intended to be used for uniform workloads. Here is a section from the Guidelines for Working with Tables documentation and some other helpful links about the best practices:

    A temporary non-uniformity in a workload can generally be absorbed by the bursting allowance, as described in Use Burst Capacity Sparingly. However, if your application must accommodate non-uniform workloads on a regular basis, you should design your table with DynamoDB's partitioning behavior in mind (see Understand Partition Behavior), and be mindful when increasing and decreasing provisioned throughput on that table.

  3. This one is going to depend on how much data your table has, because DynamoDB will have to repartition the data if you are scaling up. See the Consider Workload Uniformity When Adjusting Provisioned Throughput documentation for more information about the partitioning..

Upvotes: 2

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