During the recent Ignite conference, Microsoft announced Azure Cosmos DB for PostgreSQL, a new generally available (GA) service to build cloud-native relational applications. It is a distributed relational database offering with the scale, flexibility, and performance of Azure Cosmos DB.

Azure Cosmos DB is a fully managed NoSQL database with various APIs targeted at NoSQL workloads, including native NoSQL and compatible APIs. With the support of PostgreSQL, the service now supports relational and NoSQL workloads. Moreover, the company states that Azure is the first cloud platform to support both relational and NoSQL options on the same service.

The PostgreSQL support includes all the native capabilities that come with PostgreSQL, including rich JSON support, powerful indexing, extensive datatypes, and full-text search. Next to being built on open-source Postgres, Microsoft enabled distributed query execution using the Citus open-source extension. Furthermore, the company also stated in a developer blog post that as PostgreSQL releases new versions, it will make those versions available to its users within two weeks. 

Source: https://devblogs.microsoft.com/cosmosdb/distributed-postgresql-comes-to-azure-cosmos-db/

Developers can start building apps on a single node cluster the same way they would with PostgreSQL. Moreover, when the app's scalability and performance requirements grow, it can seamlessly scale to multiple nodes by transparently distributing their tables. A difference compared to Azure Database for PostgreSQL, which Jay Gordon, a Microsoft Azure Cosmos DB senior program manager, explains in a tweet:

#AzureCosmosDB for #PostgreSQL is a distributed scale-out cluster architecture that enables customers to scale a @PostgreSQL workload to run across multiple machines. Azure Database for PostgreSQL is a single-node architecture.

In addition, the product team behind Cosmos DB tweeted:

We are offering multiple relational DB options for our users across a number of Database services. Our Azure Cosmos DB offering gives you PostgreSQL extensions and support for code you may already be using with PostgreSQL.

And lastly, Charles Feddersen, a principal group program manager of Azure Cosmos DB at Microsoft, said in a Microsoft Mechanics video:

By introducing distributed Postgres in Cosmos DB, we’re now making it easier for you to build highly scalable, cloud-native apps using NoSQL and relational capabilities within a single managed service.

More service details are available through the documentation landing page, and guidance is provided in a series of YouTube videos. Furthermore, the pricing details of Azure Cosmos DB are available on the pricing page.