Microsoft began making SQL Server 2008 available to users today, slightly behind schedule but still making good on its goal of releasing an upgrade to its flagship database within three years of shipping the previous version.

The software vendor released the new database to manufacturing and said that MSDN and TechNet subscribers can download the 1GB package immediately. Other users will be able to download evaluation versions of SQL Server 2008 starting tomorrow, according to Microsoft's announcement.

In addition to a raft of added features, SQL Server 2008 includes a new edition aimed at Web hosting firms, which Microsoft is more aggressively cultivating in response to the growing demand for hosted and cloud-computing services.

Microsoft also plans to move its still-in-beta SQL Server Data Services (SSDS) hosted database offering, which currently is based on an internal CloudDB powered by SQL Server 2005, to the new version shortly, said Ted Kummert, corporate vice president of Microsoft's data and storage platforms division.

SQL Server was the fastest-growing major database last year, according to market-research firm IDC, which reported that sales of the database increased 14 per cent during 2007 -- putting Microsoft slightly ahead of the growth rates of top database rivals Oracle and IBM.

But with SSDS and the new Web hosting edition added into the mix, Microsoft soon will offer five different versions of SQL Server, the others being the free Express offering and its Standard and Enterprise editions. Won't the two new offerings start cannibalizing existing customers? Not according to Fausto Ibarra, director of SQL Server product management, who maintains that they will only help Microsoft to accelerate SQL Server's sales growth.

Noel Yuhanna, an analyst at Forrester Research, isn't so sure about that.

"I think SSDS will compete against Express and the Standard edition, but for now, SSDS is targeting a different audience," Yuhanna wrote in an e-mail. "The good thing about SSDS is you don't have to worry about backup, storage, performance, availability, etc., which I think is great for SMBs or small applications." SSDS also is more cost-effective than the Standard and Express editions of SQL Server, he said, and it is "optimized for data sharing that can be accessed from anywhere using a browser."

SSDS currently requires users and developers to use Web 2.0 protocols such as REST and SOAP or Microsoft's LINQ language to interact with and extract data, in contrast with the typically SQL-based applications developed for the on-premises versions of SQL Server.

But Kummert promised that developers eventually will be able to write applications once and port them between SSDS and the other versions of SQL Server with minimal changes. "Our intent is to provide a consistent application model," he said, adding that Microsoft will provide "more clarity" on how it will do so over "the next year or so."