https://yellokat.github.io/posts/%EC%B6%94%EC%B2%9C%EC%8B%9C%EC%8A%A4%ED%85%9C-%EB%85%BC%EB%AC%B8-%EB%A6%AC%EB%B7%B0-monolith-real-time-recommendation-system-with-collisionless-embedding-table/