- It is a relational database-as-a-service (DBaaS) based on the latest stable version of Microsoft SQL Server Database Engine.
- The Azure SQL Database service is only available through TCP port 1433.
- Connections from Azure virtual machines are redirected to a different IP address and port, unique for each worker role.
- A logical server acts as a central administrative point for multiple single or pooled databases, logins, firewall rules, auditing rules, threat detection policies, and failover groups.
- It is the parent resource that provides a namespace for databases, elastic pools, and data warehouses.
- It is a logical container with strong lifetime semantics - delete a server and it deletes the contained databases, elastic pools, and data warehouses.
- It provides a connection endpoint for database access (
**.database.windows.net**).
- A logical server is a logical construct that is distinct from a SQL Server instance that you may be familiar with in the on-premises world.
- The SQL Database service makes no guarantees regarding location of the databases in relation to their logical servers
- It exposes no instance-level access or features.
- In contrast, a server in a SQL Database Managed Instance is similar to a SQL Server instance that you may be familiar with in the on-premises world.
- A logical server can be in a different region than its resource group.
- All databases on a server are created within the same region as the logical server.
- It must exist before you can create the Azure SQL database.
- It is a capability providing near 100% compatibility with SQL Server on-premises (Enterprise Edition).
- It provides a native virtual network (VNet) implementation and a business model favorable for on-premises SQL Server customers.
- It allows existing SQL Server customers to lift and shift their on-premises applications to the cloud.
- It also preserves all PaaS capabilities such as automatic patching and version updates, backup, and high-availability.
- Managed Instance is available in two service tiers:
- General Purpose: Designed for applications with typical performance and IO latency requirements.
- Business Critical: Designed for applications with low IO latency requirements and minimal impact of underlying maintenance operations.
- Both service tiers guarantee 99.99% availability and enable you to independently select storage size and compute capacity.
- It is a simple, cost-effective solution for managing and scaling databases that have varying and unpredictable usage demands.
- The databases in an elastic pool are on a single server and share a set number of resources at a set price.
- It enables the price performance for a group of databases while delivering performance elasticity for each database.
- A common pattern is to provision a single database per customer.
- Different customers often have varying and unpredictable usage patterns which makes it difficult to predict the resource needed for each database.
- Traditionally, you had two options to address this:
- Over-provision resources based on peak usage and over pay.
- Under-provision to save cost, at the expense of performance and customer satisfaction during peaks.