If I had to guess from looking at his git repo, he's referring to LMDB:: http://symas.com/mdb/ http://symas.com/mdb/ sqlite and lmdb aren't exactly equivalent

If I had to guess from looking at his git repo, he's referring to LMDB:: http://symas.com/mdb/ http://symas.com/mdb/ sqlite and lmdb aren't exactly equivalent, but I guess that is his point; you can gain a lot of performance just by understanding your use case and what tradeoffs you can make.