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Billing for DynamoDB On-Demand

1

I see the pricing Read and Write requests pricing for a DynamoDB table in N. Virginia is:

Write Request Units (WRU) $1.25 per million write request units Read Request Units (RRU) $0.25 per million read request units

Does this mean that with each request, the number of request units (for either) grows toward a million, then once it does reach a million, I get charged? E.g., I make a request that's 8 WRU, then a second one that's also 8 WRU and that puts me at 16 WRU, so I have less than a million WRUs left.

If that's the case, does it reset every month, or is it static?

Topics
ServerlessComputeDatabaseStorageCloud Financial Management
Tags
ServerlessHigh Performance ComputeAmazon DynamoDBStoragePricing
Language
English
Mike
asked 4 months ago697 views
2 Answers
2

It's the same as buying gas. If the price is $4 per gallon and you fill half a gallon, it costs $2.

16 WRUs gets charged 16 / 1,000,000 * $1.25

AWS
jzhunter
answered 4 months ago
  • Mike
    4 months ago

    That makes things a tad bit clearer. The problem is, I don't know the rate at which the WRU charge is happening. In other words, how often am I getting charged 16 / 1,000,000 * $1.25? It isn't specified anywhere that I've read. But I got the answer. Thank you for your response!

  • jzhunter
    4 months ago

    You can consider the charge as immediate, although the actual bill comes later. The bill may summarize usage as sums of hourly or daily consumption.

1

Hi

No, that's not quite how DynamoDB on-demand billing works. Here's how it actually charges:

  • You are billed for the total number of read and write request units (RU) your table consumes per hour, not accumulated towards a million.
  • Each request consumes a specific amount of RU depending on its size and type of operation (read vs write, strongly consistent vs eventually consistent).

For example a write request that modifies 1 KB of data consumes one write RU, and a strongly consistent read of 4 KB data consumes one read RU.

So, in your example, if each of your requests consumes 8 RU (which is unlikely), you'll be billed for 16 RU for that hour if those are the only requests made. This billing resets every hour, not every month.

Pricing for On-Demand Capacity - Amazon DynamoDB:

Amazon DynamoDB On-Demand – No Capacity Planning and Pay-Per-Request Pricing

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EXPERT
Ganesh Kudikala
answered 4 months ago
  • Mike
    4 months ago

    Oh okay, so it's per hour. The documentation page (and product page for that matter) are not clear on that. They just say how much gets charged, but not at what rate. Thank you for your response!

    Regarding the last piece of your answer though... Doesn't an eventually consistent read of an item up to 64 KB = 8 read RUs? Unless I'm just butchering the math/logic, isn't it likely to receive 64 KB of data in a single request?

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