The scalability improvements of SQL Azure were announced last week as part of an opening keynote talk at Tech-Ed in New Orleans. Customers will be able to tap 50 GB maximum using Microsoft's Internet cloud-based relational database management system, starting on June 28. In addition, Microsoft added the ability to store spatial data-types using the SQL Azure service.
Microsoft offers two pricing plans for SQL Azure users: a lower cost Web Edition and a Business Edition. The Web Edition costs $9.99 per month for a relational database of 1 GB. Greater capacity at 5G is also available under this plan for $49.95 per month.
The Business Edition starts with a 10 GB relational database at the low end of the scale for $99.99 per month. Greater capacity is available in 10-GB increments for $100 more at each increment. Consequently, at the high end of the scale, it costs $499.95 per month for a 50 GB relational database.
A description of the SQL Azure price changes is provided by Microsoft here. Overall costs associated with the Windows Azure platform are listed in this table. Microsoft provides its own description of how it charges for SQL Azure services in this FAQ.
The actual type of data stored in SQL Azure doesn't affect the price. Instead, the price depends on the plan used and the relational database size, including "the amount of data passed into and out of the datacenter," according to Rob Sanfilippo, research vice president for developer and tools & strategies at Directions on Microsoft, a consultancy organization.
"Writes to the database will incur $0.10/GB of data transferred in, and reads from the database will incur $0.15/GB of data transferred out," Sanfilippo stated in an e-mail.
In addition, Microsoft calculates the charges on a per-day basis as part of the monthly service plan. The lowest cost plan, using a 1 GB relational database, does not incur a flat fee of $9.99 per month. Instead, the costs can vary depending on use.
"For example, if you deploy a 1 GB database ($9.99/month) for ten days of one month, your database fee for that month will be $3.33 ($9.99 x 10 days / 30 days)," Sanfilippo explained.
Microsoft includes the master database at no additional cost with the SQL Azure service. Sanfilippo explained that the master database "is a system-level database present on every SQL Server instance," so Microsoft just doesn't charge for the space it takes up on the SQL Azure platform.
Microsoft automatically backs up instances of databases on SQL Azure as part of the service, according to Sanfilippo. Such backups protect against data corruption or hardware failure on SQL Azure. Those wanting additional backup protections face additional costs.
"Customers should still consider backing up databases [on SQL Azure] to protect against bugs in their own software that may corrupt their data, requiring a rollback to an earlier state," Sanfilippo explained. "A backup created by a customer would incur additional charges."
Microsoft offers a service level agreement of 99.9 percent uptime for SQL Azure. It's based on the "connectivity between the database and our Internet gateway," according to Microsoft's SLA description.
On Aug. 1, Microsoft plans to begin a promotional offer for SQL Azure Business Edition users. Under the new "SQL Azure Development Accelerator Core" promo, Business Edition users can buy a 10-GB relational database increment for $74.95 per month, or 25 percent off the regular price. The deal is good for a six-month period, but the terms can be renewed.
One catch is that Microsoft charges overage costs if users exceed the increment paid for under the SQL Azure Development Accelerator promo, as described here.
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