This document provides an overview of MongoDB, an open-source, schema-free, document-oriented database. It discusses how MongoDB offers more flexibility and scalability compared to traditional RDBMS systems. Key features covered include dynamic queries, replication, auto-sharding, and support for many platforms/languages. Examples are given for common operations like creating, querying, and updating document structures in MongoDB.

1. open-source, high-performance,
schema-free, document-oriented
database

3. RDBMS
• Great for many applications
• Shortcomings
• Scalability
• Availability
• Flexibility

4. Key-value stores

5. CouchDB

6. JSON-style documents

7. Schema-free
• Loosening constraints - added flexibility
• Dynamically typed languages (RuPy!)
• Migrations

8. Dynamic queries
• Administration
• Ease of development
• Familiarity

9. Focus on performance

10. Replication

11. Auto-sharding

12. Many supported
platforms / languages

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

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

15. MongoDB Basics

16. Document
• Unit of storage (think row)
• BSON (Binary JSON)
• Represented as a dict / Hash

17. Collection
• Schema-free equivalent of a table
• Logical groups of documents
• Indexes are per-collection

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

19. Blog back-end

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

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

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

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

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

25. Last 10 posts
query = db.posts.find()
.sort(“date”, DESCENDING)
.limit(10)
for post in query:
print post[“text”]

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

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

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

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

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

31. Migration: adding titles
• Easy - just start adding them:
post = {“author”: “mike”,
“date”: datetime.datetime.utcnow(),
“text”: “another blog post...”,
“tags”: [“conference”, “rupy”],
“title”: “Review from RuPy”}
post_id = db.posts.save(post)

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

33. Other cool stuff
• Aggregation and map reduce
• Capped collections
• Unique indexes
• Mongo shell
• GridFS
• MongoKit, Mongoid, MongoMapper, etc.

34. Sharding

35. Terminology
• Shard key
• Chunk
• Range of the value space
• (collection, key, min_val, max_val)
• Shard
• Single node (or replica pair)
• Responsible for set of chunks

36. client

37. mongos
client

38. Shards
mongod mongod mongod
...
mongod mongod mongod
mongos
client

39. Shards
mongod mongod mongod
...
mongod mongod mongod
mongos mongos ...
client

40. Shards
mongod mongod mongod
...
Config mongod mongod mongod
Servers
mongod
mongod
mongod mongos mongos ...
client

42. • Download MongoDB
http://www.mongodb.org
• Try it out
• Let us know what you think!
• Oh, and get stickers!

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