> Fundamentally, a schema is a guarantee that your data conforms to the structure you intend. My opinion : The reality is that you never have enough informati

> Fundamentally, a schema is a guarantee that your data conforms to the structure you intend. My opinion : The reality is that you never have enough information about how the data will be queried and connected together in the long run. A table structure is a model you built from a snapshot of your knowledge of the reality, but your knowledge changes over time and so should the model. As new information goes, some assumptions made before become obsolete, while new assumptions need to be made. Even if a SQL relational database works OK for most of the business cases, they are not good at frequently evolving over time with new information or needs. They are also not that good if you have different models of the data that must exist in parallel. I could see database schema as a specialized form of organizing knowledge, but it shouldn't be considered the best and only one. Fundamentally, if you think you can fit the complexity of the reality in a bunch of relational tables, you are starting with the wrong assumptions already