Presentation on MongoDB given at the Hadoop DC meetup in October 2009. Some of the slides at the end are extra examples that didn't appear in the talk, but might be of interest.

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

3. JSON-style documents

4. Schema-free
• Loosening constraints - added flexibility
• Dynamically typed languages
• Migrations

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

6. Focus on performance

7. Replication

8. Auto-sharding

9. Many supported
platforms / languages

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

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

12. Quick example:
blog back-end

13. Post
{author: “mike”,
date: new Date(),
text: “my blog post...”,
tags: [“mongodb”, “dc”, “hadoop”]}

14. Comment
{author: “eliot”,
date: new Date(),
text: “great post!”}

15. New post
post = {author: “mike”,
date: new Date(),
text: “my blog post...”,
tags: [“mongodb”, “dc”, “hadoop”]}
db.posts.save(post)

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

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

18. Last 10 posts
db.posts.find()
.sort({date: -1})
.limit(10)

19. Posts in the last week
last_week = new Date(2009, 9, 9)
db.posts.find({date: {$gt: last_week}})

20. Sharding

21. 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

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

25. • Download MongoDB
http://www.mongodb.org
• Try it out
• Let us know what you think

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

27. Posts ending with
‘Hadoop’
db.posts.find({text: /hadoop$/})

28. Posts with a tag
db.posts.find({tag: “mongodb”})
... and fast
db.posts.ensureIndex({tag: 1})

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: new Date(),
text: “another blog post...”,
tags: [“meetup”, “hadoop”],
title: “Review from Hadoop DC”}
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’”})