RocksDB abstraction. RocksDB is an embeddable persistent key-value store
for fast storage. There is no concept of tables in RocksDB. In fact, a
RocksDB is like a table in HBase. In this class, we create a higher level
concept of database that contains multiple RocksDB databases in a directory.
Each RocksDB is actually a subdirectory, which is encapsulated in RocksTable.
RocksDB abstraction. RocksDB is an embeddable persistent key-value store for fast storage. There is no concept of tables in RocksDB. In fact, a RocksDB is like a table in HBase. In this class, we create a higher level concept of database that contains multiple RocksDB databases in a directory. Each RocksDB is actually a subdirectory, which is encapsulated in RocksTable.