Stateful workloads, especially databases, have always been framed as problematic on Kubernetes. In this talk, we want to clear up this misconception by showing that Kubernetes is highly extendable and is in fact used to host ClickHouse, an OLAP column-oriented database, at scale for our DBaaS offering.

We discuss a variety of mechanisms and extensions built on top of existing Kubernetes logic that helps us run, update and scale databases for our customers with zero downtime. Throughout this talk, we discuss what we call MultiSTS (the usage of multiple StatefulSets) and MBB (Make-Before-Break) and how those concepts helped us overcome challenges with stock Kubernetes primitives, particularly for our requirement to always provide full capacity to our customers.

In this case study, attendees will gain insights into the challenges and solutions posed by running a successful hosted database service on Kubernetes. They will take away the toolset to extend Kubernetes for database workloads.