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Google started the trend of LSM with its release of leveldb. But leveldb hasn't been updated in a long time. Facebook forked leveldb and renamed it to rocksdb. Those are the only two LSM databases I know of, and IMO they are really the same thing. Meanwhile, lmdb vs. rocksdb/leveldb is a frequently asked question that seems to have no clear answer. Test on your hardware to find the best solution for your use case.

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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

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.

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