Talk about MongoDB, PyMongo and integrating MongoDB w/ Django from the DC Python Meetup group.

1. open-source, high-performance,
schema-free, document-oriented
database
http://www.mongodb.org/

2. “One size fits all”
no longer
RDBMS
(Oracle, MySQL)
Non-relational
New gen. OLAP
(vertica, aster, greenplum) operational stores
(“NoSQL”)

3. NoSQL really means:
non-relational next generation
operational datastores and databases

4. Scaling out
no joins +
light transactional semantics =
horizontally scalable architectures

5. Data models
no joins +
light transactional semantics =
horizontally scalable architectures
important side effect :
new data models =
improved ways to develop
applications

7. Documents and BSON
{“hello”: “world”}
{“hello”: “world”, “foo”: [{“bar”: 1}]}

8. Schema-free collections
• Dynamically typed languages
• Migrations
• Still define indexes per collection

9. Dynamic queries
• Administration
• Ease of development / familiarity

10. Atomic update modifiers

11. Focus on performance

12. Replication
Replica sets
Master - slave
master slave
master
master slave
slave slave slave
master master
slave
slave master

13. Auto-sharding
Shards
mongod mongod mongod
...
Config mongod mongod mongod
Servers
mongod
mongod
mongod
mongos mongos ...
client

14. Many supported
languages and platforms

15. Good at
• The web
• Caching
• High volume data
• Scalability

16. Less good at
• Highly transactional
• Ad-hoc business intelligence
• Problems that require SQL

17. _id
• Special key
• Present in all documents
• Unique across a Collection
• Any type you want

18. Post
{“author”: “mike”,
“date”: datetime.datetime.utcnow(),
“text”: “my blog post...”,
“tags”: [“mongodb”, “python”]}

19. Comment
{“author”: “eliot”,
“date”: datetime.datetime.utcnow(),
“text”: “great post!”}

20. New post
post = {“author”: “mike”,
“date”: datetime.datetime.utcnow(),
“text”: “my blog post...”,
“tags”: [“mongodb”, “python”]}
post_id = db.posts.save(post)

21. Embedding a comment
c = {“author”: “eliot”,
“date”: datetime.datetime.utcnow(),
“text”: “great post!”}
db.posts.update({“_id”: post_id},
{“$push”: {“comments”: c}})

22. Posts by author
db.posts.find({“author”: “mike”})

23. Last 10 posts
db.posts.find()
.sort(“date”, DESCENDING)
.limit(10)

24. Posts in the last week
last_week = datetime.datetime.utcnow() +
datetime.timedelta(days=-7)
db.posts.find({“date”: {“$gt”: last_week}})

25. Posts ending with
‘Python’
db.posts.find({“text”: re.compile(“Python$”)})

26. Posts with a tag
db.posts.find({“tags”: “mongodb”})
... and fast
db.posts.create_index(“tags”)

27. Counting posts
db.posts.count()
db.posts.find({“author”: “mike”}).count()

28. Basic paging
page = 2
page_size = 15
db.posts.find().limit(page_size)
.skip(page * page_size)

29. Migration: adding titles
• Easy - just start adding them:
post = {“author”: “mike”,
“date”: datetime.datetime.utcnow(),
“text”: “another blog post...”,
“tags”: [“meetup”, “python”],
“title”: “MongoDB @ DC Python”}
post_id = db.posts.save(post)

30. Advanced queries
• $gt, $lt, $gte, $lte, $ne, $all, $in, $nin
• where()
db.posts.find().where(“this.author == ‘mike’ ||
this.title == ‘hello’”)
• group()

31. Other cool stuff
• Aggregation and map reduce
• Capped collections
• Unique indexes
• Mongo shell
• GridFS

32. ?

33. Yes...
...but also sometimes no

34. Similar to +
• A lot of Django doesn’t depend on django.db:
• URL dispatch, templates, I18N, caching, etc.
• Some things do:
• Models
• Auth
• Sessions
• Admin

35. settings.py
DATABASE_ENGINE = ''
DATABASE_NAME = ''
DATABASE_USER = ''
DATABASE_PASSWORD = ''
DATABASE_HOST = ''
DATABASE_PORT = ''
MIDDLEWARE_CLASSES = (
'django.middleware.common.CommonMiddleware',
# 'django.contrib.sessions.middleware.SessionMiddleware',
# 'django.contrib.auth.middleware.AuthenticationMiddleware',
)
INSTALLED_APPS = (
# 'django.contrib.auth',
'django.contrib.contenttypes',
# 'django.contrib.sessions',
'django.contrib.sites',
)

36. Representing a Poll
{'question': 'Do MongoDB + Django <3 each other?',
'pub_date': datetime.datetime(2010, 1, 21),
'choices': [{'votes': 35, 'choice': 'Yes!'},
{'votes': 2, 'choice': 'No...'}]}

37. models.py (PyMongo)
def save_poll(question):
return db.polls.insert({"question": question,
"pub_date": datetime.utcnow()})
def all_polls():
return db.polls.find()
def add_choice(poll_id, choice):
db.polls.update({"_id": poll_id},
{"$push": {"choices": {"choice": choice,
"votes": 0}}})
def add_vote(poll_id, choice):
db.polls.update({"_id": poll_id},
{"$inc": {"choices.%d.votes" % choice: 1}})
http://api.mongodb.org/python

38. models.py (MongoKit)
class Poll(mongokit.Document):
structure = {"question": str,
"pub_date": datetime,
"choices": [{"choice": str,
"votes": int}]}
required_fields = ["question"]
default_values = {"pub_date": datetime.utcnow}
http://bytebucket.org/namlook/mongokit

39. models.py (Ming)
class Poll(ming.Document):
class __mongometa__:
session = session
name = "polls"
_id = ming.Field(ming.schema.ObjectId)
question = ming.Field(str, required=True)
pub_date = ming.Field(datetime.datetime,
if_missing=datetime.datetime.utcnow)
choices = ming.Field([{"choice": str,
"votes": int}])
http://merciless.sourceforge.net/

40. mango - sessions and auth
• Full sessions support
• mango provided User class
• supports is_authenticated(), set_password(), etc.
http://github.com/vpulim/mango

41. mango - sessions and auth
SESSION_ENGINE = 'mango.session'
AUTHENTICATION_BACKENDS = ('mango.auth.Backend',)
MONGODB_HOST = 'localhost'
MONGODB_PORT = None
MONGODB_NAME = 'mydb'
http://github.com/vpulim/mango

42. What about admin?
• No great solution... yet.
• Could replace admin app like mango does
for sessions / auth
• Or...

43. Supporting MongoDB
in django.db
• Best solution (long term)
• http://bitbucket.org/kpot/django-mongodb/
• http://bitbucket.org/wkornewald/django-nonrel/
• http://code.djangoproject.com/wiki/NonSqlBackends

44. 1. Download MongoDB
http://www.mongodb.org
2. Try it out!
3. Let us know what you think.

45. NoSQL Live from Boston
Thursday, March 11
http://www.10gen.com/events

46. • http://api.mongodb.org/python
• http://www.mongodb.org
• irc.freenode.net#mongodb
• mongodb-user on google groups
• @mongodb, @mdirolf
• mike@10gen.com