I tried to learn Q/KDB+ more than once with only online resources and I think this book is definitely something needed. The available wiki was always a bit spar

I tried to learn Q/KDB+ more than once with only online resources and I think this book is definitely something needed. The available wiki was always a bit spare and some parts didn't work in the free package you can download for personal use. KDB is very interesting and I always had the feeling, if you stare long enough at the code you kinda learn a different way to express algorithms and a different view for how to write code. APL and its successors are probably one of those things that Alan Perlis talked about when he said that you should only learn a programming language that changes your way of thinking. On the other hand: I don't know why but it somehow bothers me that KDB+ is not open source. I'm not even someone that demands for anything to be open source and I don't actually use KDB besides thinking about learning it every now and then but it really keeps me off.