Using LSM tree like LevelDB as a storage Engine for RDBMS

Question

LSM Tree has been found successful use in many no-sql engines, its data are sorted by keys not like hashing tables thus enabling many potential use beyond a kv store. For example, a time series database (TSDB) may be a good fit using level db as its engine. How about traditional RDBMS and many table systems? Is LSM-tree like data engines are a good fit as well?

Answer 1

It might be. If you're going to design indexes in a way to exploit strengths of leveldb (namely fast sequential reading) then it might work well.

In fact I have build small relational database on top of leveldb (linqdb) where index is just sorted values of column stored as key-values. My findings are that querying such structure isn't as fast as sqlite's indexed columns (about 40% slower) but writing outperforms by a big margin.

Of course there are many factors in query speed, LSM is just an underlying data structure which best shines at writing.

Additional info here