Case de uso de MongoDB e Rails para geolocalização, apresentado na trilha NoSQL do TDC2010.

1. Geolocalização com
mongoDB e Rails
e outros nosql em startups
Maurício Maia @mauricio

2. vitrines de produtos

3. cache de produtos

4. mongoDB > MySQL > Cassandra

6. Yahoo! Open Hack Day
março 2010

7. PlaceHacker
Sinatra, MongoDB, mongo-ruby-driver

9. Topical
PlaceHacker rewrite
Rails 3
MongoDB
Mongoid
Reconhecimento de Entidades

10. Topical
Mapa de notícias

11. Topical
Stream de notícias locais

12. Topical
Mobile

13. Por que mongoDB?
fácil
flexível
cases
geospatial indexing

14. Cases
analytics, real-time, documentos, geo-location

15. Show me the code!

16. Preparando
$ gem install mongoid --pre
$ gem install bson_ext
Gemfile
gem "mongoid", "2.0.0.beta.16"
gem "bson_ext", "1.0.4"
$ rails generate mongoid:config

17. Geospatial Indexing
class Article
include Mongoid::Document
include Mongoid::Timestamps
field :title, :type => String
field :lead, :type => String
field :published_at, :type => Time
field :location, :type => Array
index [[ :location, Mongo::GEO2D ]], :min => 180, :max =>
180
index :published_at, Mongo::DESCENDING
end
db.articles.ensureIndex( { location : "2d"}, { min : -180,
max : 180 } )

18. Querying
near
Article.near(:location => [ -23.552314, -46.6500949 ])
db.articles.find( { location : { "$near" : [-23.552314,
-46.6500949 ] } } )

19. Querying
within center
Article.where(:location.within => { "$center" =>
[ [ -23.552314, -46.6500949 ], 10 ] })
db.articles.find({location : {"$within" : {"$center" :
[ [-23.552314, -46.6500949 ] , 10]}}})

20. Querying
within box
box = [ [40, 40], [60, 60] ]
Article.where(:location.within => { "$box" => box })
box = [[40, 40], [60, 60]]
db.articles.find({location : {"$within" : {"$box" : box}}}

21. Alternativas?
Geohash
PostGis (PostgreSQL)
SpatialLite (SQLite)

22. Just Build It: You don't need anyone's approval and in
fact, you probably won't get it, so don't even try
Kevin Rose - Digg