There is a free 32bit version of kdb available (http://kx.com/software-download.php). For the commercial version, pricing information is not publically available.
The zip files on that page contain the source for kdb, I thought I'd take a look at how it works.... nope! That is impenetrable
It's impenetrable to you, in the same way Mandarin is impenetrable at first glance to someone used to reading Latin languages.
The thing with KDB is almost all uses of it are in memory deployments. It isn't hard to make something that has little persistence or relegates persistence to a 2nd class citizen to run quickly.
Well, but it does not exists as open source.
no, but std::map does
Certainly, but it does not provide the same benefits as the complete package.