1. Apache
CouchDB

2. Relax

3. Hello
• J Chris Anderson
• Apache CouchDB committer
• Web programmer (Rails, Ajax, etc)
• Director, couch.io

4. About You?
• Web developers are easy
• Scalable key/value store
• Peer-based Replication
• Append-only IO pattern

5. Scaling Up
• Hot. Literally.
• You don’t have to think.

6. X
Scaling Up
• Hot. Literally.
• You don’t have to think.

7. Scale Enforces Constraints
• Distributed key / value stores
• Context is expensive
• No joins or autoincrement
• Eventual consistency

8. e Web Scales

9. Why CouchDB?
Native to the Web
Local data == low latency
Replicated applications
Scale from a cluster to a smartphone

10. Of the Web
Let me tell you something: Django may be built
for the Web, but CouchDB is built of the Web.
I've never seen software that so completely
embraces the philosophies behind HTTP. ... this
is what the software of the future looks like.
Jacob Kaplan-Moss
October 19, 2007
http://jacobian.org/writing/of-the-web/

11. Robust
JSON
HTTP
Local

12. Robust Storage
Append Only
File Structure
Designed to Crash
Instant-On

13. Happy IO Patterns

14. JSON Documents
{
"_id": "BCCD12CBB", Schema Free
"_rev": "1-AB764C",
"type": "person",
"name": "Darth Vader",
Self-Contained
"age": 63,
"headware":
["Helmet", "Sombrero"], JavaScript Map
}
"dark_side": true
Reduce Views

15. Map Reduce Views
Docs
{ “user” : “Chris”,
Map
{ “key” : “Alice”, “value” : 5 }
“points” : 3 } { “key” : “Bob”, “value” : 7 }
{ “user” : “Joe”, function(doc) { { “key” : “Chris”, “value” : 3 }
“points” : 10 } if (doc.user && doc.points) { { “key” : “Joe”, “value” : 10 }
{ “user” : “Alice”, emit(doc.user, doc.points); { “key” : “Mary”, “value” : 9 }
“points” : 5 } }
{ “user” : “Mary”, }
“points” : 9 }
{ “user” : “Bob”, Reduce
“points” : 7 }
Alice ... Chris: 15
function(keys, values, rereduce) { Everyone: 34
return sum(values);
}

16. JavaScript Map Reduce

18. ful 
You already know the API
Use existing HTTP tools
Talk directly to the browser

19. ful 
CRUD
• Create
HTTP PUT /db/mydocid
• Read
HTTP GET /db/mydocid
• Update
HTTP PUT /db/mydocid
• Delete
HTTP DELETE /db/mydocid

20. Clustering w/
CouchDB-Lounge
Partitioning / clustering proxy
Nginx module
Twisted Python query merge
Makes many machines into one Couch

21. Local Data
Low latency (fast)
Peer-based incremental replication
View source --> Open source

22. Gives Control to Users
CC-BY-SA http://www.flickr.com/photos/kelleys/492253912/

23. Bandwidth Explosion

30. “no bars”

31. http://www.flickr.com/photos/hercwad/2290378571/

33. http://www.flickr.com/photos/mcpig/872293700/

34. Latency Sucks

35. Scaling Down
4 MB RAM

36. Erlang
Parallel
Fault tolerant
Addictive
Ninja Syntax

37. Browser Couch
JavaScript port
Uses HTML5 storage
Replicates with CouchDB
http://hg.toolness.com/browser-couch/

38. No SQL
in
HTML5

39. Incremental Replication

54. Document Oriented
Not Relational
• Documents in the Real World™
• Bills, letters, tax forms…
• Same type != same structure
• Self contained
• Can be out of date (so what?)
• No references

55. Document Oriented
Not Relational
• Documents in the Real World™
Bills, letters, tax forms…
Natural Data
•
• Same type != same structure
•
Behaviour
Can be out of date (so what?)
• No references

59. Render JSON Docs as HTML
shows/post.js /drl/_design/sofa/_show/post/Hello-World-For-Real-This-Time

61. Render Views as HTML
lists/index.js /drl/_list/sofa/index/recent-posts?descending=true&limit=8

70. anks!

71. Resources
@CouchDB
http://couchdb.apache.org/
Dress like a Couch: http://shop.couchdb.com
http://planet.couchdb.org/
https://peepcode.com/products/couchdb-with-rails

72. @couchdbinaction
http://books.couchdb.org/relax

73. couch.io
Berlin – London – Portland

74. CC-by-nd http://www.flic.kr/photos/eifelyeti110/273939759/