Azure SQL Database is a general-purpose relational database based on the latest Enterprise Edition of SQL Server. A fully managed SQL database engine, Azure SQL Database service is your platform as a service solution. That means you don’t have to worry about updates, patching, or managing the hardware, and it’s a great option when you need to get to market fast.
Within Azure SQL Database service, you have a couple of deployment options.
Single Databases
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single database is one with its own set of resources, including guaranteed compute size. A single database is portable and isolated from other databases. It is also optimized for the development of cloud-based applications. A serverless option is available which allows the database to “spin down”. When a database spins down, you not charged for compute resources only for consumed storage. Or you can go with a provisioned model where compute resources are available to your application at all times.
The dynamic scalability of a single database makes it a great option when you’re building your first app in the cloud. You can develop your app on a small, single database at a low cost in the serverless compute tier or a small compute size in the provisioned compute tier, and then change the compute or service tier at any time without downtime.
SQL Database Elastic Pool
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SQL Database elastic pool is a set of resources that are shared by a collection of databases and managed via a database server. If you need to manage and scale multiple databases that have fluctuating usage, elastic pools are a simple and cost-effective way to do so. You can easily move single databases in and out of an elastic pool as well as limit resources to individual databases so as to not consume the entire pool. Like single databases, elastic pools are optimized for the development of new cloud-based applications but using the multi-tenant software as a service model.
Whether you choose a single database or an elastic pool, before you create an Azure SQL Database, you must first create an
Azure SQL Database server. As the central administrative point for multiple single or pooled databases, the Azure SQL Database server is used to manage logins, backups, firewall rules, auditing rules, threat detection policies, active geo-replication, and fail-over groups.
Unlike in the on-premises world, a SQL Database server is distinct from a SQL Server instance. While all databases managed by a SQL Database server are created within the same region, the SQL Database service makes no guarantees regarding the location of the databases in relation to the server that manages them. Nor does the SQL Database server expose any instance-level access or features. Finally, a SQL Database server can be in a different region than its resource group.