Scalable Linear Algebra on a Relational Database System (2020)
cacm.acm.org
cacm.acm.org
So all the operations described in the article, and more are implemented here https://github.com/apache/madlib/tree/master/src/ports/postg...
I'm not sure why Madlib is not mentioned in that CACM article
[0]: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.157...
I liken it to how we used to test on how to sort and merge data, with the answer being that it is always a trade off. Which is exactly what an execution plan is. More, index projections is half of the magic developers relearn every year.
To that end, getting linear algebra primitives easily accessed in a query language feels like it will be a game changer.