Other TS products like OneTick, RDBMSs for TAQ (esp. if you need non-TS indexes), streambase for UI backends
I even met a programmer who hacked something together in Java using the same columnar kdb layout but, you know, multithreaded, so different basket optimization jobs could run simultaneously on the same store.
Single machine, because it can't handle parallel queries, at all, and there are no options to scale it.
Every financial institution I've worked at is busily unwinding their investment in q/kdb. It's legacy tech.