Shortly after version 16 of PostgreSQL was released, CosmosDB follows suit adopting the new version applicable to production workloads.
Back in November last year and in Azure CosmosDB for PostgreSQL Reaches General Availability we watched the first steps of CosmosDB extending beyond NoSQL by adding support for PostgreSQL. That move rendered Azure the first cloud provider to offer its own single database service that supports both relational and NoSQL workloads.
Initially Cosmos supported MongoDB, Apache Gremlin and Apache Cassandra before adding support for PostgreSQL, and you could choose the desired API when creating a cluster. So while Cosmos DB for NoSQL did not have relational constraints, when needing to work with relational workloads you could choose the Postgres backend, a fully managed distributed SQL offering built upon the core benefits of Postgres like JSONB datatype extensions, PostGIS, rich indexing and so on.
Last November Cosmos was in tune with PostgreSQL version 15 but now also adds support for 16. What rendered the update easy, is the open source Citus extension which on top of that enables Postgres to be fir for the distributed scale by using distributed tables across multiple nodes.
Needles to say, Cosmos also gets all the goodies coming with version 16 such as :
query performance improvements with more parallelism
developer experience enhancements;
monitoring of I/O stats using pg_stat_io view; and
enhanced security features
An added advantage of hosting Cosmos on Azure, is that creating a new database for PostgreSQL gives you many new capabilities. Example features include:
High Availability across Availability Zones (AZ)
Automatic backup/restore & ability to rewind to a particular point-in-time
One-click upgrade to latest PostgreSQL & extension versions
Scale up/down your CPU and storage resources
Encryption at rest and private endpoints
Compliance with global and local certifications across 30 Azure regions
Global distribution across Azure regions to tolerate regional failures
It's easy to get started with creating your first Cluster is good enough, and although the official documentation is good to start with, there's also a free, self-paced course which gives you the chance to expand your knowledge of Azure Cosmos DB as well as earn a certification. Check Take the Azure Cosmos DB Cloud Skills Challenge for more details on that.