Azure SQL Database

Deployment and Management

Deployment

Instant provisioning of a database via portal/CLI – ready in minutes, no VM or OS to manage (fully platform-managed).

Management

Fully managed by Azure – Microsoft handles all patching and maintenance.

Customization

Very restricted – no OS or instance access, only DB-scoped settings; cannot use unsupported features (e.g., CLR, xp_cmdshell).

Use Case

Best for new cloud-native apps, SaaS, and scenarios requiring zero infrastructure management – modern applications that can live within one DB (or use sharding/pools).

Maintenance and Operations

Maintenance Responsibility

Microsoft – fully automatic patch management and updates (you don’t even see it happening).

Operational Control

Partial – you have db_owner on your databases and a contained “server” admin, but many instance-level features aren’t available (no control over master/tempdb beyond some settings).

Backups

Automated: full PITR backups are done by Azure (e.g., every 5-10 min log backups); long-term retention can be configured for weekly/monthly/yearly backups.

Scalability and Performance

Scalability

Vertical: move between DTU/vCore tiers easily (some operations online); Horizontal: scale out by sharding or using multiple databases (Elastic Pool), or use readable geo-replicas – not transparent sharding, app must handle if needed.

Performance

Excellent for typical workloads, with options to choose higher tiers if needed: Business Critical has low-latency SSD and 2-4 replicas for read, Hyperscale can scale out readers and handle very large DBs. The platform handles tuning, but you might sacrifice some extreme tuning (e.g., can’t control file placement).

Elasticity

Yes (Serverless option) – Azure SQL DB serverless will auto-scale CPU/RAM within set bounds and even pause the DB on inactivity, providing true on-demand elasticity. For provisioned databases, you can scale with an API call (not automatic, but quick) and use Azure Automation to schedule or trigger it.

Features and Capabilities

SQL Server Version

Azure SQL Database always runs the latest stable SQL Server engine managed by Microsoft. It doesn’t match a specific legacy version but supports compatibility levels up to 160 (SQL 2022) for older T-SQL compatibility.

SQL Feature Support

Azure SQL DB supports most SQL features but lacks SQL Agent, CLR assemblies, FILESTREAM, and cross-database transactions. Features like JSON, Full-Text Search, In-Memory OLTP, and Temporal Tables are fully supported.

Cross-Database Queries

No (not directly): each Azure SQL DB is isolated. Cross-DB joins require external tables or client-side join logic. Azure provides elastic query which is essentially a workaround (create external data source to another DB). So it’s not as seamless as on a full instance.

Custom Software

No – you get only the database environment. If you need something like a specialized full-text extender or a custom compression DLL, you can’t install that on Azure SQL DB. You’d have to move to MI or VM if installation is required.

Network and Security

Network Configuration

By default, accessible over the internet with a secure endpoint (you restrict by firewall rules). If needed, use Private Link to bring it into your VNet with a private IP. You don’t see or manage the underlying network, but you can control connectivity at a high level (public/private).

Security

Azure SQL DB enforces TDE for data at rest, encrypted connections, and compliance with PCI DSS, HIPAA, etc. Auditing and Advanced Threat Protection enhance security, while Private Link restricts network access. As a multi-tenant service, OS-level access is not available, but Microsoft ensures data isolation and certification compliance.

Authentication

Supports SQL authentication and Azure AD authentication, allowing Azure AD users to log in with modern identity management and MFA. Traditional Windows AD accounts require syncing to Azure AD for authentication.

High Availability and Disaster Recovery

High Availability

Azure SQL DB provides built-in HA with at least three replicas: General Purpose uses Azure storage redundancy, while Business Critical employs a 3-4 node Always On quorum with 99.99% SLA. Failovers are automatic with minimal impact.

Disaster Recovery

Supports Active Geo-Replication with up to 4 readable replicas in different regions. Failover can be manual or automated via Auto-Failover Groups. If not configured, point-in-time restore to another region serves as a DR option.

Pricing and Licensing

Pricing

Azure SQL DB pricing is based on compute (vCores or DTUs) and storage. An 8 vCore General Purpose database with 4TB costs ~$1,800/month, while Business Critical is 2-3× higher due to extra replicas and SSDs. Hyperscale storage is charged per GB, but compute is similar to General Purpose. SQL licensing is included.

Licensing Model

Azure SQL DB follows a license-included model, but Azure Hybrid Benefit reduces costs if you bring existing licenses. Billing is pay-as-you-go or reserved capacity (1-3 years). There are no CALs, and Enterprise Edition (SA) holders get cost breaks on Business Critical.

Pricing Comparison of Database Configuration

8vCore + 4TB Data size + Backup,  Single Instance

An 8 vCore, 4TB General Purpose Azure SQL DB costs ~$1,800/month ($1,400 compute + $400 storage).
Switching to Business Critical raises the price to $4,000–$5,000/month. Hybrid Benefit can cut vCore costs by ~40%.

8vCore + 4TB Data size + Backup + DR/HA

HA is included at no extra cost. For DR, a geo-replicated secondary (8 vCore GP instance) adds ~$1,800/month, bringing total costs to $3,600/month.
Auto-Failover Groups require paying for both primary & secondary. Business Critical geo-secondaries cost the full BC rate.