An elastic pool is a logical container that can host multiple databases in a single logical server. The SKUs available for elastic pools are as follows:

• Basic
• Standard
• Premium

The following screenshot shows the maximum amount of DTUs that can be provisioned for each SKU:

All the features discussed for Azure SQL single instances are available to elastic pools as well; however, horizontal scalability is an additional feature it provides with the help of shading. Shading refers to the vertical or horizontal partitioning of data and the storing of it into separate databases. It is also possible to have auto-scaling of individual databases in an elastic pool by consuming more DTUs than are actually allocated to that database.

Elastic pools also provide another advantage in terms of cost. We will see in a later section that Azure SQL is priced using the concept of DTUs, and DTUs are provisioned as soon as the SQL Server service is provisioned. DTUs are charged for irrespective of whether those DTUs are consumed. If there are multiple databases, then it is possible to put these databases into elastic pools and they can share the DTUs among them.