In this presentation, I will delve into the intricacies of database refactoring, with an emphasis on my personal experience. I will cover the importance of refactoring in maintaining the performance and scalability of databases, as well as various challenges I have encountered and the solutions I've implemented while working with databases of tens and hundreds of terabytes in size. I will also discuss the best practices and tools that I have found to be the most effective in this process. Examples will be based on SQL Server, PostgreSQL, HBase and Apache Cassandra/ScyllaDB background.