The general problem, which is rooted in computer science, is that there is no data structure that could be optimized for any kind of possibly query [language |

The general problem, which is rooted in computer science, is that there is no data structure that could be optimized for any kind of possibly query [language | algorithm]. One corollary of this is that you need to look at the problem you want to solve and decide. I don't think SQL is obsolete but I think it is not the iption for every kind of problem. Specially in HN there are a lot of discussions about "big data", "data science", AI.