Lago - Using Clickhouse to Scale an Events Engine

Lago, an open-source usage-based billing platform, switched from a Postgres-only database stack to a hybrid one with ClickHouse for streamed events and Postgres for other data needs. The decision was made due to the heavy load times experienced as they began ingesting millions of events per minute. They chose ClickHouse because it is an OLAP (online analytical processing) database designed for efficiently answering complex read queries with approximate accuracy and batch processing a large number of write queries. Lago's performance improved significantly after moving to ClickHouse, with some main queries showing improvements of up to 137x. Other open-source projects that have made the switch from Postgres to ClickHouse include PostHog and GitLab.