I try different to serialize my data before saving into RocksDB.
real 4m11.713s user 13m32.809s sys 1m33.887s
real 2m13.772s user 10m45.541s sys 1m41.670s
real 10m54.622s user 22m11.570s sys 1m10.663s
real 2m52.010s user 12m17.019s sys 1m32.687s
CBOR and bincode are obviously faster than JSON and S-Expression. CBOR is a less efficient than bincode. However, more programming languages support CBOR.