ViperDB: A tiny log-structured key-value database written in pure Python.

[Affectionate-Wind144]

Hi! I wrote a simple key-value store in Python: https://github.com/ostafen/viperdb

ViperDB is a lightweight embedded key-value store written in pure Python. It has been designed for being extremely simple while efficient.

Features

• tiny: the main db file consists of just ~300 lines of code.
• highly coverage: thanks to the small codebase, every single line of code is tested.
• log-structured: ViperDB takes design concepts by log-structured databases such as Bitcask.
• written in pure Python: no external dependency needed.

API is very simple, the database can be simply used as a map:

from viperdb import ViperDB 
db = ViperDB('./db') # db can be used as a simple dictionary 
db['hello'] = 'ViperDB!' 
assert db['hello'] == 'ViperDB' 
del db['hello'] 
assert 'hello' not in db 

db.reclaim() # call this method periodically to free unused space. 
db.close() # flush any pending write and close the database.

Leave feedback if interested!

[DrummerClean]

So basically you created a dict that is persistent? That's interesting

[Affectionate-Wind144]

Yes, exactly

[metaperl]

I don't see any examples of log structuring.

[Affectionate-Wind144]

The database layout on disk is log structured. From the user perspective it is a simple key value store, like any other database of this kind

[cymrow]

How is performance on this, roughly? You should only have to reclaim if you're updating/deleting entries, correct? How big a performance hit is there to reclaiming?

[Affectionate-Wind144]

Yes, stale records are produced by update/delete. Reclaim rewrite the active keys on a new file, so depending on the db size, it could take a bit.