[rakoo]

It primarily depends on your requirements, as a rule of thumb:

* If your workload is random-writes heavy, choose lsm

* If your workload is serial-writes heavy, both are similar

* If your workload is read-heavy (random or not) go for lmdb

[hyc_symas]

If your writes are larger than ~1/2 a page, LSMs are slower, regardless of random or sequential access pattern.

http://lmdb.tech/bench/ondisk/

Also, if your writes are mostly smaller than ~1/2 a page, you can reduce your B+tree pagesize and regain performance.