SQL Database PaaS Deployment Options

 

Single Database : This is a single isolated database that is perfect for applications that need a single data source. We create this against a database server and it has its own set of assigned resources. This could be in terms of a database transactional unit, a DTU.

Elastic Pool: An Elastic Pool is a collection of single databases with a shared set of resources such as CPU or memory. We create an Elastic Pool against that logical database server. The benefit here is that each database could have varying level of resource requirement at different times because it's sharing that pool. In the Elastic Pool scenario, there's a fixed amount of resources which would be shared by all the databases in the pool.

 

Managed Instance : A managed instance is a set of databases that can be used together. Allows easy migration from on premises databases. This is a dedicated instance of SQL Server running in your virtual network. Now the resources are provisioned at the managed instance database server level and then all of the instance databases running on that managed instance database server share whatever resources are available.