TL;DR Practical usage of database technologies has drifted quite far from academical theory we've (or at least I've) been taught at universities. In my case some lessons learned were pretty much contrary to opposite to what I've believes was correct as a fresh graduate. This blog post is about them - e.g. why redundancy may be advantageous, deleting any data is wrong or updates in place should be replaced with aggregate switching. I'm one of these people who've built their professional career in software engineering on prior academic knowledge gained during studies on technical university. I'm proud of…