How is SimpleDB priced?

Amazon provides a free tier for SimpleDB along with pricing for usage above the free tier limit. The charges are based on the machine utilization of each SimpleDB request along with the amount of machine capacity that is utilized for completing the specified request normalized to the hourly capacity of a 1.7 GHz Xeon processor.

Free tier

As of the publication date of this book, there are no charges on the first 25 machine hours, 1 GB of data transfer, and 1 GB of storage that you consume every month. This is a significant amount of usage being provided for free for this limited time period by Amazon, and there are many kinds of applications that can operate entirely within this free tier. Pricing details are available at http://aws.amazon.com/simpledb/.

While a credit card is required to sign up, usage can be checked at any time with the Amazon Account Activity web page. Amazon estimates about 2,000,000 GET or SELECT API calls per month without any charge.

The pricing details might make it a bit daunting to figure out what your costs may be initially, but the free tier provided by Amazon goes a long way toward getting you more comfortable using the service and also putting SimpleDB through its paces without significant cost. There is also a nice calculator provided on the AWS site that is very helpful for computing the monthly usage costs for SimpleDB and the other Amazon web services. You can find the Amazon web services cost calculator at http://calculator.s3.amazonaws.com/calc5.html.