The environment around Jd has changed a bit since it was young! Jsoftware[0] announced it in 2012, and this particular page has been effectively the same since

The environment around Jd has changed a bit since it was young! Jsoftware[0] announced it in 2012, and this particular page has been effectively the same since it was created in 2017 (I suspect this was a page move, and the content is somewhat older). In these early days the column-oriented database was quickly gaining popularity but still obscure, which is why there's this "Columnar" section that goes to so much trouble to explain the concept. Now the idea is well known among database users and there are lots of other options[1]. The history goes back further, because column-oriented is the natural way to build a database in an array language (making a performant row-oriented DBMS would be basically impossible). This is because a column can be seen as a vector where every element has the same type. A row groups values of different types, and array languages don't have anything like C structs to handle this. In J, Jd comes from Chris Burke's JDB proof-of-concept (announced[2] 2008, looks like), and the linked page mentions kdb+ (K) and Vstar (APL). KDB, first released in 1993, is somewhat famous and gets a mention on Wikipedia's history of column-oriented databases[3]. [0] Company history: https://aplwiki.com/wiki/Jsoftware https://aplwiki.com/wiki/Jsoftware [1] https://en.wikipedia.org/wiki/List_of_column-oriented_DBMSes https://en.wikipedia.org/wiki/List_of_column-oriented_DBMSes [2] https://code.jsoftware.com/wiki/JDB/Announcement https://code.jsoftware.com/wiki/JDB/Announcement [3] https://en.wikipedia.org/wiki/Column-oriented_DBMS#History https://en.wikipedia.org/wiki/Column-oriented_DBMS#History