Talk on MongoDB at local Ruby meetup

2. Getting started with
MongoDB

3. Introduction

4. Introduction
Relational
Database

5. Introduction
Document
Relational
Orientated
Database
Database

6. Introduction
Document
Relational
Orientated
Database
Database
NoSQL Bra.

7. What is MongoDB?
• Scalable high-performance open source, document-
orientated database
• Built for speed
• Rich document based queries
• Full index support
• Replication and Failover
• Auto Sharding
• Map / Reduce

8. Why use MongoDB?
• SQL was invented in the 70’s to store data
• MongoDB stores documents / objects
• We work with objects (Ruby)
• We need databases to persist our objects
• So why not just store objects directly?

9. What its great for
• Websites
• Caching
• High scalability
• Storage of program objects and JSON

10. What its not great for
• Highly transactional applications
• Problems requiring SQL

11. Differences

12. When I Say
Database

13. When I Say Think
Database Database

14. When I Say Think
Database Database
• Made up of multiple collections
• Are created on-the-fly when first referenced

15. When I Say
Collection

16. When I Say Think
Collection Table

17. When I Say Think
Collection Table
• Schema-less
• Indexable by one or more keys
• Created on-the-fly when first referenced
• Capped collections: Fixed size, older records dropped after
limit reached

18. When I Say
Document

19. When I Say Think
Document Record / Row

20. When I Say Think
Document Record / Row
• Stored in a collection
• Can have _id key - Works like primary keys in MySQL
• Supports relationships: embedded or referential
• Document storage in BSON

21. When I Say Think
Document Record / Row
• Stored in a collection
• Can have _id key - Works like primary keys in MySQL
• Supports relationships: embedded or referential
• Document storage in BSON
JSONS Binary Brother

22. Relations

23. Referential / Normalised
• Same as SQL
• “First class” objects that are at top level
• Many to many relationships
has_many
User Blog Post
belongs_to

24. # Post
{
title: “Getting started with MongoDB”,
body: “blah blah blah ... “,
created: Date(’09-06-2010’),
tags: [1, 2]
}
# Comments # Tags
{
{
id: 1,
body: “I did not have relations..”,
name: “example”
user_id: 1,
},
{
post_id: 1,
id: 2,
created: Date(’09-06-2010’),
name: “lol”
}
}

25. Embedded
• Embedded is pre-joining
• Embed when document always appears with parent
• 4MB document size limit
Blog Post
Post Title
Post Body
Comments

26. # Posts
{
title: “Getting started with MongoDB”,
body: “blah blah blah ... “,
created: Date(’09-06-2010’),
Array tags: [ ‘example’, ‘bill clinton’ ],
comments: [
{ author: “Bill”, comment: “I did not have relations” },
{ author: “Monica”, comment: “LOL” }
]
}
Array of hashes

27. Ruby MongoDB

28. MongoMapper
http://github.com/jnunemaker/mongomapper
• Typecasting
• Callbacks (ActiveSupport Callbacks)
• Validations
• Connection and database can differ per document
• Has create, update methods
• Find: id, ids, :all, :first, :last
• Associations (has_one, has_many, many_to_many)

29. http://www.mongoid.org
• Named scopes / chainable criteria
• Versioning of your documents
• Full callback support on documents AND embedded
documents
• Proper master/slave distribution
• Optimised for use with extremely large datasets
This is what we use!

30. Demo

31. Conclusions
• NoSQL is pretty scary / We’re used to SQL
• It’s the future.

32. Chat to us online:
twitter: @platform45

33. Discussion