The database access, in conjunction with Amazon's Simple Storage Service (S3) and Elastic Compute Cloud (EC2) application hosting, provides services that the company said will make Web-scale computing "easier and more cost-effective for developers ."

Users only pay for what they use, at the rate of 14 cents per machine hour used. The machine hours are determined by measuring the use required for every request, on the basis of the capacity of a current-generation 1.7-GHz Xeon processor .

In addition, there are charges for data in and out, starting at 10 cents per GB in and 18 cents per GB out, although data transferred to other Amazon Web Services is free.

Eliminating Traditional Costs

Amazon said that, traditionally, this type of functionality has used a clustered relational database, with considerable investment, complexity, and management requirements. "Many developers," the company said in a statement, "simply want to store, process, and query their data without worrying about managing schemas, maintaining indexes, tuning performance , or scaling access to their data."

Amazon said that its SimpleDB can be automatically indexed for "fast real-time lookup and querying capabilities." It compared a SimpleDB domain to a spreadsheet table, with items as rows of data, attributes as column headers, and values as the data in each cell. Administrative complexity is simplified through a set of APIs for storing, processing, and querying data, and the costs of software licenses, hardware , and resource management are removed.

If a full relational database is needed, the company added, developers can host their own inside the Amazon EC2 environment.

Amazon Like Google

Brad Shimmin, an analyst with Current Analysis, said that Amazon "is doing what Google is doing -- becoming a provider of hosted services." In Google's eyes, he added, "90 percent of the world's software will someday be online," and both companies are intending to leverage their "phenomenal infrastructure to enable this kind of ecosystem." For enterprises that can't afford to build out their own data centers, Shimmin said, services such as Amazon's can be an important asset.

Amazon's prominence as an Internet company could help propel the growth of accessible computing resources "in the cloud ," for database, storage , processing and other needs. Besides Google, companies that offer some form of database-as-a-service include Caspio Bridge, Dabble DB, Freebase, QuickBase, and Nenest. Cloud-based computing is also being explored by Microsoft , IBM, and others.