This is pretty similar to Sparkey[0] and bam[1]. Sparkey also comes from growing out of cdb's limitations. It supports block-level compression like Riffle does, and is optimized for accepting bulk writes. Riffle's linear-time merge behavior lifted from Sorted String Tables is a nice alternative to accepting writes at runtime. bam is cool in that it takes a plain separated values file as input, and builds an index file from a minimal perfect hash function over the input file.

[0]: https://github.com/spotify/sparkey [1]: https://github.com/StefanKarpinski/bam