I wonder how many people actually have seen those index card shelves[1] IRL. Everyone have heard enough of music box analogy, the Tacoma Narrows, etc, but I don

I wonder how many people actually have seen those index card shelves[1] IRL. Everyone have heard enough of music box analogy, the Tacoma Narrows, etc, but I don't remember this technology covered often enough. One set of shelves has cards for books sorted by its ISBN. Another by titles, by authors, by keywords, ... libraries(of books, of employee records, of manufacturing blueprints...) would have had whole rooms worth of these shelves for searching and indexing. Data normalization, SELECT, and JOIN, are just separating information on cards into separate shelves, hand picking cards, and laying out matching ones side by side on photocopiers. I've never had to mess with it, but apparently that was literally the database. 1: https://en.wikipedia.org/wiki/Library_catalog https://en.wikipedia.org/wiki/Library_catalog