LevelDB has two key architectural principles—immutability and speed in writing. The immutability is subtle but important to understand—data is never updated in LevelDB. Instead, it is marked as deleted or superseded by a new copy. From the application code, this may seem like a moot point, as you seem to be updating key values. However, it is vital to understanding the database structure and following behavior described.
With your newly gained experience in LevelDB programming, we will study the implementation with an eye to tunable aspects. More details and file formats are explained in the code comments and the files in the
doc folder of the LevelDB source.
We will discuss the settings for tuning and the places ...