compact abstract method
Compact the underlying storage for the key range *begin,*end.
In particular, deleted and overwritten versions are discarded,
and the data is rearranged to reduce the cost of operations
needed to access the data. This operation should typically only
be invoked by users who understand the underlying implementation.
beginKey == null is treated as a key before all keys in the database.
endKey == null is treated as a key after all keys in the database.
Therefore the following call will compact the entire database:
LevelDB.compact(null, null)
Implementation
void compact(RawData beginKey, RawData endKey);