Read/Write Capacity Unit in AWS DynamoDB - Price per hour

Question

I have recently explored AWS DynamoDB and was reading about Read/Write Capacity Units. I understood that they are as under:

• WCU: A write capacity unit represents one write per second, for an item up to 1 KB in size.
• RCU: A read capacity unit represents one strongly consistent read per second, or two eventually consistent reads per second, for an item up to 4 KB in size.

So, my table has 1 WCU and 1 RCU. This means I would be charged for every read and every write I do to my table. Good so far. Plus I would be charged additionally for data storage.

However, when I look at this link (scroll down to DynamoDB detailed feature pricing/Read and Write Requests), it shows me WCU and RCU in Price per hour which is $0.00065 per WCU or $0.00013 per RCU.

What is the meaning or Price per hour?

Would I be wrong to assume $0.00065 per WCU or $0.00013 per RCU and ignore the hour part completely? Meaning, per write would cost me $0.00065 and per read would cost me $0.00013.

Answer 1

There are two pricing models for DynamoDB: Provisioned and On-Demand.

Provisioned capacity means that you will be charged each hour for the provisioned unit whether you consume it or not -- and your requests will be throttled if you go over provisioned capacity in a given second. This model allows for considerable savings when you have stable demand and you have a method within your solution to deal with throttles gracefully.

If you are in the dev mode, or your application has unpredictable peaks, you should consider On-Demand mode where you will be billed a flat rate per request irrespectively of the rate of requests.

Hope this helps.