Lesson 1: The Azure Database Map: Every Service on One Page

Why start with a map

Ask five engineers which Azure database to use and you will hear old names: "Cosmos DB vCore", "Azure Cache for Redis", "Single Server". Some of those products have been renamed. Some are closed to new projects. A few no longer exist. If you pick one of them in a design review today, you can lose a quarter to a migration that was predictable from the start.

This level gives you a one-page map. Every Azure database service goes into one of seven groups. For each one you will note:

1. the engine it is closest to
2. its current name and any former names
3. whether it is open to new projects, and if not, where Microsoft sends you instead

Think of it as a supermarket aisle map. Before you read labels, you need to know which aisle the product is in.

The map

Gotcha: "Cosmos DB" is a family, not one database. The NoSQL, MongoDB (RU), Table, Cassandra and Gremlin APIs share the Cosmos DB account and its request-unit (RU) billing model. Azure DocumentDB was carved out of that family and now has its own name and a compute-plus-storage pricing model. When someone says "we use Cosmos", ask which API.

Gotcha: two Cassandras. Managed Instance for Apache Cassandra runs real Cassandra nodes for you. Cosmos DB for Apache Cassandra is Cosmos DB answering CQL. They behave differently under load and are billed differently. Later levels cover the details.

The retirements to flag

Azure Cache for Redis. Microsoft is moving everyone to Azure Managed Redis:

• Basic, Standard and Premium: creation was blocked for new customers on 1 Apr 2026 and for existing customers on 1 Oct 2026. The tiers retire on 30 Sep 2028.
• Enterprise and Enterprise Flash: creation was blocked on 1 Apr 2026. These tiers retire on 31 Mar 2027.

In practice, you cannot start a new project on Azure Cache for Redis today.

Azure Cosmos DB for PostgreSQL. It is no longer supported for new projects. The retirement notice of 30 Mar 2026 sets retirement for 31 Mar 2029 and points to elastic clusters in Azure Database for PostgreSQL. Both run on the same Citus extension.

Already gone: Single Server for PostgreSQL and for MySQL, Azure Database for MariaDB, and Time Series Insights. If a runbook or blog post tells you to create one of these, it is out of date.

Walkthrough: map your own subscription

Names in slides go stale. Names in Azure Resource Manager are what is really running. This query lists every database-type resource in a subscription. It uses Azure Resource Graph, so you need the resource-graph CLI extension.

# One-time setup: install the Resource Graph extension
az extension add --name resource-graph

# List database resources across the subscription, grouped by type
az graph query -q "
Resources
| where type in~ (
  'microsoft.sql/servers/databases',            // Azure SQL Database
  'microsoft.sql/managedinstances',             // SQL Managed Instance
  'microsoft.sqlvirtualmachine/sqlvirtualmachines', // SQL Server on VMs
  'microsoft.dbforpostgresql/flexibleservers',  // PostgreSQL flexible (incl. elastic clusters)
  'microsoft.dbforpostgresql/servergroupsv2',   // Cosmos DB for PostgreSQL (retiring)
  'microsoft.dbformysql/flexibleservers',       // MySQL flexible
  'microsoft.documentdb/databaseaccounts',      // Cosmos DB (NoSQL, MongoDB RU, Table, Cassandra, Gremlin)
  'microsoft.documentdb/mongoclusters',         // Azure DocumentDB (ex-vCore)
  'microsoft.documentdb/cassandraclusters',     // Managed Instance for Apache Cassandra
  'microsoft.cache/redis',                      // Azure Cache for Redis (retiring)
  'microsoft.cache/redisenterprise',            // Azure Managed Redis AND old Enterprise tier
  'microsoft.kusto/clusters')                   // Azure Data Explorer
| project name, type, resourceGroup, location, sku = tostring(sku.name)
| order by type asc" -o table

The output will look something like this:

Name           Type                                   ResourceGroup  Location    Sku
-------------  -------------------------------------  -------------  ----------  -----------
cache-legacy   microsoft.cache/redis                  rg-shop        uksouth     Standard
amr-sessions   microsoft.cache/redisenterprise        rg-shop        uksouth     Balanced_B1
catalog-docs   microsoft.documentdb/mongoclusters     rg-shop        uksouth

How to read it:

• cache-legacy is on a retiring service. Add it to the migration backlog now.
• catalog-docs shows as mongoClusters even though the portal now calls it Azure DocumentDB. The resource type kept its old name, so your templates and policies do not have to change.

Trade-off to remember: redisenterprise covers both Azure Managed Redis and the retiring Enterprise tier. Check the SKU to tell them apart. Balanced_B1 is Managed Redis. A name like Enterprise_E10 is the old tier, which retires in March 2027.

Blind spot: SQL database in Fabric lives in a Fabric workspace, not in an Azure resource group, so this query will not find it. Oracle Database@Azure resources appear under the Oracle.Database provider; add or type startswith 'oracle.database' if you use it.

Key takeaways

• There are seven groups: relational, distributed SQL, key-value and document, wide-column, in-memory, graph and time series, and migration. Put a service in its group before you compare anything else.
• Azure DocumentDB is the former Azure Cosmos DB for MongoDB (vCore). Cosmos DB for MongoDB (RU) is a separate service that is still part of Cosmos DB.
• Azure Cache for Redis is retiring and new caches cannot be created. Use Azure Managed Redis.
• Cosmos DB for PostgreSQL is not for new projects and retires on 31 Mar 2029. Use PostgreSQL elastic clusters.
• Single Server (PostgreSQL and MySQL), MariaDB and Time Series Insights are already retired. Their successors are flexible server, MySQL flexible server and Azure Data Explorer.
• Check what is actually deployed with Resource Graph, and watch for resource types that kept their old names.