Azure Databases — Azure SQL, Managed Instance, Cosmos DB, PostgreSQL and Migration Cheat Sheet

Azure Databases — Azure SQL, Managed Instance, Cosmos DB, PostgreSQL and Migration

Choosing a database on Azure; Azure SQL Database (single database, elastic pools, DTU vs vCore, General Purpose / Business Critical / Hyperscale, serverless), Azure SQL Managed Instance and SQL Server on Azure VMs; security (firewall, private endpoints, Microsoft Entra authentication, managed identity, TDE, Always Encrypted, auditing), high availability, geo-replication, failover groups and backups/point-in-time restore; performance (Query Store, automatic tuning, Intelligent Insights); Cosmos DB (APIs, partition keys, RU/s, consistency levels), Azure Database for PostgreSQL/MySQL, Azure Cache for Redis; migrating on-premises SQL Server (DMA, Azure Database Migration Service) and cost optimisation.

Choose the service

New app → Azure SQL Database · lift-and-shift with Agent/cross-DB → Managed Instance · full control/SSRS on box → SQL VM · global NoSQL → Cosmos DB · Postgres/MySQL → Flexible Server · cache → Redis.

Azure SQL tiers

DTU (Basic/Standard/Premium) or vCore (General Purpose, Business Critical, Hyperscale) · serverless (auto-scale, auto-pause) · elastic pools (many DBs) · Hybrid Benefit + reservations.

Security

Private endpoint · Entra-only auth + managed identity (Authentication=Active Directory Default) · TDE · Always Encrypted · RLS · auditing · Defender for SQL.

HA/DR

Built-in HA (99.99 %) · zone redundancy · geo-replication · failover groups (listener endpoints) · PITR 1–35 days · LTR up to 10 years · geo-restore · retry transient faults.

Cosmos DB

Partition key (high cardinality, in queries) · RU/s (autoscale/serverless) · consistency: Strong → Bounded → Session (default) → Prefix → Eventual · change feed · point reads cheapest.