Abstract: RisingWave is an open-source streaming database designed from scratch for the cloud. It implemented a Snowflake-style storage-compute separation architecture to reduce performance cost, and provides users with a PostgreSQL-like experience for stream processing. Over the last three years, RisingWave has evolved from a one-person project to a rapidly-growing product deployed by nearly 100 enterprises and startups. But the journey of building RisingWave is full of challenges. In this talk, I'd like to share with you lessons we've gained from four dimensions: 1) the decoupled compute-storage architecture, 2) the balances between stream processing and OLAP, 3) the Rust ecosystem, and 4) the product positioning. I will dive deep into technical details and then share with you my views on the future of stream processing.