Well, a form of 80's "sql" pushed out the more elegant upgrade for "sql". aka forerunner which postgress is based on. Perhaps something that doesn't require both a degree in underlying theory and degree in practical use application.

Updated 70's pre-sql , non-postgres example:

Kleene[0] / de brujin[1] programming a complete database system from scratch (pawk/neovim) using ebnf/bnf in place of more modern data structures with an wasm compiled awk /python for browser use might make postgres seem like a darling. Makes for lot of academic/discussion material though; something original 70's sql was trying to avoid/work around.

[0]a : https://ai.dmi.unibas.ch/_files/teaching/fs16/theo/slides/th...

[0]b : https://www.cl.cam.ac.uk/teaching/0708/MathCompTh/kleene.pdf

[1] : https://en.wikipedia.org/wiki/De_Bruijn_graph