ClickHouse is an open-source data warehouse solution that helps companies like Admixer, a leading ad-tech company, to handle high volumes of data and provide real-time insights. Admixer was moving from MSSQL to Azure Table Storage to ClickHouse to improve its performance and scalability. The company's Advertising Exchange, which aggregates traffic from external SSPs to place local advertisements on it, required a more robust storage solution. With ClickHouse, Admixer can now handle over 1 million records per second and aggregate data for thousands of publishers. The company chose ClickHouse due to its ability to scale horizontally, provide real-time data processing, and offer cost-effective solutions. ClickHouse architecture has evolved over time, with the addition of new components such as Requests Handler, EventsProcessor, and report generation service. Admixer's experience with ClickHouse has provided valuable lessons for others considering using the solution, including the importance of load testing, choosing the right replication scheme, and monitoring performance.