I wrote a time-traveling database (where you can query a table/row as of a specific point in time and join it to data at another point in time; we used this for AI training to predict future behavior in users) completely from scratch (that was the coolest work project ever, btw) that was built on Hadoop/Hbase. I understand RocksDB is fairly similar ... however, I want to stay as far away from any of those kinds of APIs. I have scars from dealing with hbase and writing query planners and figuring out how to do performant joins in a white-room type environment. No. Thank. You.
It was fun at the time, but I don't want to go near it ever again.
[RocksDB](https://rocksdb.org/) isn’t a distributed storage system, fwiw. It’s an embedded KV engine similar to LevelDB, LMDB, or really sqlite (though that’s full SQL, not just KV)
To be perhaps overly detailed: Hbase is an open source approximation of bigtable. Bigtable _uses_ leveldb as its per-shard local storage mechanism; Rocks is a clone+extension of leveldb.
Bigtable and hbase are higher level and provide functionality across shards and machines. Level and rocks are building blocks that provide a log-structured merge tree storage and retrieval mechanism.
