#Blitz-DB
BlitzDB, or just Blitz is a document-based, object-oriented, transactional database written purely in Python. Among other things, it provides a powerful querying language, deep indexing of documents, compressed data storage and automatic referencing of embedded documents. It is reasonably fast, can be easily embedded in any Python application and does not have any external dependencies (except when using a third-party backend). In addition, you can use it as a frontend to other database engines such as MongoDB in case you should need more power.
##Key Features
- Document-based, object-oriented interface.
- Powerful and rich querying language.
- Deep document indexes on arbitrary fields.
- Compressed storage of documents.
- Support for multiple backends (e.g. file-based storage, MongoDB).
- Support for database transactions (currently only for the file-based backend).
##Use Cases
Blitz can be used as a standalone document store for client application. Originally blitz was designed for use with the checkmate Python code analysis toolkit, where it stores statistical data. Since blitz stores all documents as single JSON files, it is possible to put the whole database under version-control.
##Detailed Documentation
The detailed documentation for this project is hosted on ReadTheDocs, feel free to take a look!
##Examples
To get an idea of what you can do with Blitz, here are some examples.
###Creating objects
from blitzdb import Document
class Movie(Document):
pass
class Actor(Document):
pass
the_godfather = Movie({'name': 'The Godfather','year':1972,'pk':1L})
marlon_brando = Actor({'name':'Marlon Brando','pk':1L})
al_pacino = Actor({'name' : 'Al Pacino','pk':1L})###Storing objects in the database:
from blitzdb import FileBackend
backend = FileBackend("/path/to/my/db")
the_godfather.save(backend)
marlon_brando.save(backend)
al_pacino.save(backend)###Retrieving objects from the database:
the_godfather = backend.get(Movie,{'pk':1L})
#or...
the_godfather = backend.get(Movie,{'name' : 'The Godfather'})###Filtering objects
movies_from_1972 = backend.filter(Movie,{'year' : 1972})###Working with transactions
backend.begin()
the_godfather.director = 'Roland Emmerich' #oops...
the_godfather.save()
backend.rollback() #undo the changes...###Creating nested object references
the_godfather.cast = {'Don Vito Corleone' : marlon_brando, 'Michael Corleone' : al_pacino}
#Documents stored within other objects will be automatically converted to database references.
marlon_brando.performances = [the_godfather]
al_pacino.performances = [the_godfather]
marlon_brando.save(backend)
al_pacino.save(backend)
the_godfather.save(backend)
#Will store references to the movies within the documents in the DB###Creation of database indexes and advanced querying
backend.create_index(Actor,'performances')
#Will create an index on the 'performances' field, for fast querying
godfather_cast = backend.filter(Actor,{'movies' : the_godfather})
#Will return 'Al Pacino' and 'Marlon Brando'###Arbitrary filter expressions
star_wars_iv = Movie({'name' : 'Star Wars - Episode IV: A New Hope','year': 1977})
star_wars_iv.save()
movies_from_the_seventies = backend.filter(Movie,{'year': lambda year : True if year >= 1970 and year < 1980 else False})
#Will return Star Wars & The Godfather (man, what a decade!)