Microsoft Docs

Azure SQL Database Concepts

This section provides a comprehensive overview of the fundamental concepts behind Azure SQL Database, a fully managed relational data service that supports your application needs.

What is Azure SQL Database?

Azure SQL Database is a fully managed Platform as a Service (PaaS) database engine that handles most of the database management functions such as upgrading, patching, backups, and provides high availability without user involvement. You can focus on your application development and not on database administration.

Key benefits include:

• High Availability and Durability: Built-in redundancy and automatic failover ensure your data is always accessible.
• Scalability: Scale your database up or down based on demand without downtime.
• Intelligent Features: Performance monitoring, tuning recommendations, and automated threat detection.
• Security: Advanced security features including always-on encryption, threat detection, and dynamic data masking.
• Hybrid Capabilities: Seamlessly integrate with on-premises SQL Server environments.

Deployment Options

Azure SQL Database offers several deployment options to suit different needs:

• Single Database: An isolated database with its own set of resources managed via a logical server. Ideal for new cloud applications or modernizing existing ones.
• Elastic Pool: A collection of databases with shared resources. Useful for SaaS applications where resource usage fluctuates across databases.
• Managed Instance: A nearly 100% compatibility with on-premises SQL Server, ideal for migrating existing SQL Server workloads with minimal changes.

Compute and Storage

Azure SQL Database offers different purchasing models and service tiers to match your performance and price requirements:

• DTU (Database Transaction Unit) Model: A bundled measure of compute, I/O, and log resources. Simple to understand for small to medium workloads.
  • Basic: Entry-level performance for small workloads.
  • Standard: Moderate performance for most common applications.
  • Premium: High performance for mission-critical applications with high transaction rates.
• vCore (Virtual Core) Model: Allows you to select compute and storage resources independently. Offers more control and flexibility, especially for larger or more demanding workloads.
  • General Purpose: Balanced compute and I/O for a wide range of applications.
  • Business Critical: Highest performance and I/O capacity, with enhanced availability features.
  • Hyperscale: For very large databases (up to 100TB) requiring elastic scaling.

Logical Servers

A logical server is a management construct that acts as a central administrative point for a collection of databases. It hosts databases, logins, firewall rules, and auditing policies. It does not store data itself but provides access to the databases it manages.

Connectivity

Connecting to your Azure SQL Database typically involves:

1. Ensuring your IP address is added to the server's firewall rules.
2. Using a supported client tool or driver (e.g., SQL Server Management Studio (SSMS), Azure Data Studio, .NET, ODBC, JDBC).
3. Providing valid authentication credentials (SQL Authentication or Azure Active Directory Authentication).

Key Features

• Automatic Backups: Full, differential, and transaction log backups are performed automatically.
• Point-in-Time Restore: Restore your database to a specific point in time within the retention period.
• Active Geo-Replication: Replicate databases to secondary regions for disaster recovery or read-scale purposes.
• Failover Groups: Provide a managed disaster recovery and failover solution for multiple databases.
• Intelligent Performance: Automatic tuning, query performance insight, and index management.

Understanding these core concepts will help you effectively leverage the power and flexibility of Azure SQL Database for your applications.