I'd rather have Bitcask or RocksDB - something that has better crash recovery capabilities. LevelDB was marked as being prone to data corruption. DETS has similar problems when not closed properly.

> LMDB was marked as being prone to data corruption

Don't know where you got your information from, but LMDB is verified as the safest storage engine:

https://www.usenix.org/conference/osdi14/technical-sessions/...

Sorry, I was thing about LevelDB. ANd yes, you are right about LMDB!

DETS is supposed to repair itself on startup. I think most crash-only systems work that way (on startup, start reading from end and find last consistent bit and chop off the rest). But there could obviously been a bug there.

I have a very modest experience with it, but when a crash happened it was game-over for it. Maybe I was doing something wrong.

No. The actual ext is something you have to provide yourself.