LMDB

“By default, LMDB performs whatever necessary syncs and is 100% crash proof, even in the face of power outages.”

“Dropping the explicit P_DIRTY flag in 1.0 is a neat change.”

“Next step is go down one more level to ditch SQL and learn LMDB and/or RocksDB.”

“LMDB's hot paths fit entirely inside a CPU's L1 cache.”

“LMDB is fast despite being hobbled by vanilla kernel mmap.”

“an mmap() based page caching system will not do”

“no fine tuning is needed. The internal paths to every hot page automatically take priority”

“but then the whole database can be unrecoverable in case of crash. It has happened to me.”

“Being able to do it in parallel is necessary, especially when you have billions of entries to operate on.”

“The main issues were related to write speed but we do a compaction of the database”

“pointed out CVEs in LMDB attributed to his own bare hands”

“this latest (1.0) and the previous 0.9.x are mutually incompatible, requiring essentially a dump/restore”

“I think lmdb is mostly unusable, for many use cases.”

“That it keeps an infinite cache of malloc page allocations is annoying”

“I've used LMDB in production for multi-terabyte databases, and we encountered the long-write time but found a solution.”

“It has worked well for me as a way to read mutable (by any client) parameters during synthesis”

“LMDB does the work once and all users benefit.”

“Don't use LMDB for anything that matters.”

“we are getting inconsistent signals on how seriously they understand and implement security concerns”

“As long as you stick to the safe LMDB options, which are the default options, it's reliable.”

“once the db reached several hundred gb, writes would hang for longer and longer periods of time”

“It is really reliable except write performance in my experience.”

“iOS doesn't page dirty mmaped pages back to disk and after enough churn the app will OOM”

“It has been used successfully as the backend for OpenLDAP and Monero”

“pushing return values 4k above the stack, with a comment like”

“LMDB is already used by OpenLDAP [2][3] and seems pretty bullet-proof.”

“inspired by LMDB's blazing fast memory-mapped CoW approach”

“lightning fast on reads but quite bad on writes”

“It's truly an incredible piece of tech.”

“getting a 22x speedup by replacing SQLite's btree code with LMDB”

“Then OS will do a better job (as seen with LMDB etc”

“LMDB, boltdb/bbolt and sqlite (with mmap) are all rock solid.”

“lmdb is a bit further down the list”

“a default database that isn't robust against power failure or crashes seems suprising to me”

“if the object mapping fits in memory that should be pretty optimal for reading”

“Because it's so efficient, it can retain more useful data in-memory than other DBs for a given RAM size.”

“It will always be far more efficient than any other DB under the same conditions.”

“LMDB fully supports multiprocess concurrency as well as DBs multiple orders of magnitude larger than RAM”

“From this documentation I don't know how to use lmdb to make a correct program.”

“I find this almost totally unusable. I often find myself reading the source instead.”