I love reading about biography like these. I own a couple books, for example, "Where Wizards Stay Up Late: The Origins Of The Internet" did keep me awake for a few days on an early train. This one, absolutely easy to digest, thank you for sharing.
1. So do the four code bases share code they reuse (think of a common repository they depend on)?
2. Are the query planners all different because they needed to be platform specific?
3. Is DB2 still on four code bases?
Would be awesome if we have one central catalog of stories like this one.
BTW, I didn't know much about the author, so I did some quick googling: http://mvdirona.com/jrh/work/
(I hope HN won't flood it to 404! Mr. James, is this on AWS!? It looks like it might be.)