Azure SQL DB

Azure SQL Database (DB) is a relational database service in the cloud based on the Microsoft SQL Server DBMS engine. SQL Database delivers predictable performance, scalability with no downtime, business continuity and data protection.

Characteristics of the SQL Database deployment option:

  • It’s a highly scalable, intelligent, relational database service built for the cloud with the industry’s highest availability SLA.
  • Supports scenarios that require databases currently up to 100 TB (Feb 2022) or autoscaling for unpredictable workloads (serverless – automatically scales compute, based on workload demand, and bills only for the amount of compute used).
  • SQL Database elastic database pool feature allows all databases in the pool share the same set of compute and storage resources. Each database can use the resources it needs, within defined limits, depending on current load.
  • There are two primary pricing options for SQL Database: DTU (a combined measure of compute, storage, and I/O resources) and vCore (virtual core).
Illustration that shows a business scenario for Azure SQL Database.

SQL DB Elastic Pools

Always-On Availability Groups for Read Scale-out

The Premium and Business Critical tiers for Azure SQL Database (and Azure SQL Managed Instance) have an Always On Availability Group feature for disaster recovery and high-availability of the application. There’s a primary read-write replica, and several secondary read-only replicas. The secondary replicas are provisioned with the same compute size as the primary replica. You set the connection string option to decide whether the connection is routed to the write replica or to a read-only replica.

Hyperscale Service Tier for Azure SQL DB

The Hyperscale service tier is available only in Azure SQL Database. This service tier has a unique architecture because it uses a tiered layer of caches and page servers to expand the ability to quickly access database pages without having to access the data file directly.

Characteristics of Hyperscale architecture:

  • The Hyperscale tier architecture uses paired page servers. Can scale horizontally to put all the data in caching layers.
  • The Hyperscale architecture supports databases as large as 100 TB.
  • This tier uses snapshots, which allow for nearly instantaneous database backups, regardless of database size.
  • Database restores take minutes rather than hours or days.
  • Can scale up or down in constant time to accommodate requirements of workloads.

Additional information

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