Amazon has moved its SimpleDB online database service out of beta, claiming that new features have reduced the cost of data storage from $1.50 to $0.25 per gigabyte per month.

The Simple Database Explorer interface, available now on a 30-day free trial basis, will support a direct upload of MySQL data into SimpleDB, according to the firm.

SimpleDB forms part of Amazon Web Services, and works in close conjunction with the firm's Simple Storage Service (Amazon S3) and Elastic Compute Cloud (Amazon EC2). The combined services allow developers to collectively store, process and query data sets in the cloud.

While large objects and files are intended to be stored in Amazon S3, SimpleDB is designed to store small amounts of data and is optimised for fast data access and flexibility in how the data is expressed, Amazon said.

The company also claimed that it has made SimpleDB even simpler to use.

"You can now get started for free. For at least the next six months, you can consume up to 1GB of storage, and you can use up to 25 machine hours each month. You can transfer 1GB of data in, and another 1GB out. You can move as much data to and from Amazon EC2 as you would like, for free," said Jeff Barr, Amazon's web services evangelist, in a blog posting.

Amazon explained that it had called the database "simple" because it provide s capabilities that allow users to easily index and query data.

The indexing takes place automatically, and multiple values can be associated with each database cell, unlike a traditional spreadsheet, according to Amazon.

"There is no need to predefine a schema or change a schema if new data is added later," the company said.

Barr claimed that the SimpleDB model "really shines" in its extensive support for concurrent access. A total of 5,600 requests per second were made during a private beta carried out by developers at review and summary service provider Pluribo, according to Barr.