OK, I thought relational modelling was more niche than that, thanks. But as long as we&#x27;re on the topic of the kernel language model, I&#x27;m getting reminded of the fact that every time we add a stratification to the KL, we don&#x27;t get a _better_ language; instead we get a _different_ language, with its own set of strengths of weaknesses.<p>For example, if the relational language is the database kernel language (model?), why does the &quot;degradation&quot; towards key-value pairs benefit a cache like Redis?<p>I&#x27;m all for principles books on databases right now, so thanks, I&#x27;ll take a look.<p>EDIT: oh, CJ Date wrote &quot;Database in Depth: Relational Theory for Practitioners&quot;, which seems newer. Do you know how they compare?