Comment by geocar

kdb+/q is another really good choice for dsv[1] and json[2]. You can certainly create single-file databases (if you really want to e.g. for exchange), but splayed table[3] is faster so you'd usually do that.

[1]: http://code.kx.com/q/ref/filenumbers/#load-csv

[2]: http://code.kx.com/q/ref/dotj/

[3]: http://code.kx.com/q/cookbook/splayed-tables/