Intro to CouchDB

Ben Aldredhttp://geekmade.co.uk

@benaldred

Disclaimer• I am not a CouchDB expert• I still quite like Relational Databases

Introducing...

Apache(so it must be good, right?)

Document orientated Database

CouchDB aims to solve problems

Scaling

Storing Data

How?

CouchDB Scalesjust like rails!

Non-locking Multiversion

concurrency control (MVCC)

Replication

New way to model data

Case Study: Invoices

JSON{ "_id":"hello-world", "_rev":"AE19EBC7654", "title":"Hello World", "body":"content...", "date":"2009/12/25 15:52:20" }

JSON{ "_id":"hello-world", "_rev":"AE19EBC7654", "title":"Hello World", "body":"content...", "date":"2009/12/25 15:52:20" }

JSON{ "_id":"hello-world", "_rev":"AE19EBC7654", "title":"Hello World", "body":"content...", "date":"2009/12/25 15:52:20" }

HTTP REST APICreate: PUT /:db Read: GET /:db/:docidUpdate: PUT /:db/:docidDelete: DELETE /:db/:docid

Views

Mapfunction(doc) { if(doc.date && doc.title) { emit(doc.date, doc.title); }}

key | value-------------------------------------"2009/12/25 15:52:20" | "Hello World"

Query the Viewhttp://localhost:5984/mydb/_design/post/_view/foo

Query the Viewhttp://localhost:5984/mydb/_design/post/_view/foo

Demo

When to use CouchDB

When you need to scale

When availibility is more important than

consistency

When not to use it

You want to leaverage the power of an ORM

CouchDB + Ruby

CouchRest

Corecouch = CouchRest.new("http://127.0.0.1:5984")db = couch.database!('NWRUG')db.save_doc({ 'title' => 'Intro to CouchDB', 'speaker' => 'Ben Aldred', 'location' => 'BBC', 'tags' => ['couchdb', 'ruby']})

Moreclass Presentation < CouchRest::ExtendedDocument include ::CouchRest::Validation

property :title property :speaker property :location

validates_present :titleend

More

Presentation.firstPresentation.allPresentation.by_title(:key => 'Ben Aldred')Presentation.get('intro_to_couchdb')

More

property :questions, :cast_as => ['Question']property :speaker, :cast_as => 'Person'property :started_at, :cast_as => 'Time'

More

view_by :started_at, :descending => trueview_by :speaker, :title

Moreview_by :name, :map => "function(doc) { if(doc.date && doc.title) { emit(doc.date, doc.title); } }"

Loads More

but I have not got time

Resources•http://books.couchdb.org/relax/•http://github.com/jchris/couchrest•http://couch.io•http://labs.mudynamics.com/wp-content/uploads/2009/04/icouch.html •http://geekmade.co.uk