Berkeley DB is one of those things everyone respected, for some reason, but that didn't actually work if you threw a bit of data at it. And not just for us. I remember talking to companies that paid them lots of money to work on reliability, and it never got better. But I do remember reading much of the source (trying to figure out why it didn't work) and thinking "this is pretty nice code".
yeah - scars still visible here from a year 2000 project using BerkeleyDB. Unbelievable complexity to write adapters to ordinary desktop software.