The document introduces CouchDB, a highly concurrent, schema-free, document-based database server that utilizes a RESTful API and map/reduce views for data handling. It details key features such as easy data replication, document structure with auto-generated IDs and revisions, as well as CRUD operations for data management. Additionally, the document discusses practical use cases and replication strategies, showcasing CouchDB's versatility and application in various organizations.

1. An introduction to #CouchDB
Sit back and relax
@davidcoallier, University Limerick 2010

2. WTF IS COUCH?
- Highly concurrent database server
- Schema free, document based database
- RESTFul API
- Map/Reduce Views generation
- EASY replication (like... really)

3. ... AGAIN.. WTF?!

4. HISTORY CLASS TIME!

6. 32 CouchDB servers
2 datacenters
SSL based user auth, sharding, etc.
This is the only BBC transparent logo I found and it’s not BBC World News using CouchDB but BBC.
See: http://www.erlang-factory.com/conference/London2009/speakers/endafarrell

7. Ubuntu One

8. mozilla.org
IBM
Apple
myspace.com
ebay
meebo
oh so many more.

9. DOCUMENT BASED
KEY/VALUE STORE...

10. key value
name david
email e@e.com
phones Array
createdAt timetsamp

11. DOCUMENT BASED WHAT?
- Dictionary of data
- JSON Objects
- A doc can have attachments
- Auto generated IDs (CLAP NOW)
- Revisions (THAT’S RIGHT..)

12. DOCUMENT
{
"_id": "3fc3b3bf3c101e15fa7d08e2ecf9c900",
"_rev": "1-34c5c7adcf1fdb8898498d1e6b64ebdd",
"firstname": "David",
"email": "david@echolibre.com"
}

13. DOCUMENT
{
"_id": "3fc3b3bf3c101e15fa7d08e2ecf9c900",
"_rev": "1-34c5c7adcf1fdb8898498d1e6b64ebdd",
"firstname": "David",
"email": "david@echolibre.com",
"phones": {
"mobile": "086x209x69",
"home": "none"
},
"createdAt": "2009-09-16T22:12:43Z"
}

14. key value
name david
email e@e.com
phones Array
createdAt timetsamp

15. WHAT ABOUT MY CRUD?
- Create PUT /db/docid
- Retrieve GET /db/docid
- Update POST /db/docid
- Delete DELETE /db/docid

16. VIEWS
- Persistent representation of docs
- Prod is solid. No _temp shit.
- Javascript, Erlang, Python, wtf ever.

17. MAP/REDUCE ...

18. JAVASCRIPT

19. MAP
map: function(doc) {
if (doc.firstname) {
emit(doc.firstname, doc);
}
}

20. MAP
%% Map Function
fun({Doc}) ->
case {proplists:get_value(<<"firstname">>, Doc)} of
{undefined} ->
false;
{Name} ->
Emit(Name, Doc);
_ ->
ok
end
end.

21. fun({Doc}) ->
Emitter = fun(Doc) ->
Name = proplists:get_value(<<"name">>, Doc, null),
Emit(Name, Doc)
end,
HasRequiredFields = fun(Doc) ->
case {proplists:is_defined(<<"firstname">>, Doc)} of
{true} ->
Emitter(Doc);
_->
false
end
end,
HasRequiredFields(Doc)
end.

22. MAP/REDUCE EXAMPLE

23. MAP
{
"_id": "3fc3b3bf3c101e15fa7d08e2ecf9c900",
"_rev": "1-34c5c7adcf1fdb8898498d1e6b64ebdd",
"firstname": "David",
"email": "david@echolibre.com",
"phones": {
"mobile": "086x209x69",
"home": "none"
},
"createdAt": "2009-09-16T22:12:43Z",
"tags": ["cool", "php", "couchdb", "skynet"]
}

24. MAP
map: function(doc) {
if (doc.tags && docs.tags.length > 0) {
for (var i = 0; i < doc.tags.length; i++) {
emit(doc.tags[i], 1);
}
}
}

25. REDUCE
map: function(doc) {
if (doc.tags && docs.tags.length > 0) {
for (var i = 0; i < doc.tags.length; i++) {
emit(doc.tags[i], 1);
}
}
},
reduce: function(tag, counts) {
int sum = 0;
for(var i = 0; i < counts.length; i++) {
sum += counts[i];
}
return sum;
}

26. REDUCE
function(tag, counts) {
int sum = 0;
for(var i = 0; i < counts.length; i++) {
sum += counts[i];
}
return sum;
}

27. REDUCE
{
"total_rows":4,
"rows":[
{ "key":"cool",
"value":1},
{ "key":"php",
"value":1},
{ "key":"couchdb",
"value":1},
{ "key":"skynet",
"value":1},
]
}

28. REDUCE TRICKS
map: function(doc) {
if (doc.tags && docs.tags.length > 0) {
for (var i = 0; i < doc.tags.length; i++) {
emit(doc.tags[i], 1);
}
}
}
reduce: "_count"

29. REDUCE
{
"total_rows":4,
"rows":[
{ "key":"cool",
"value":1},
{ "key":"php",
"value":1},
{ "key":"couchdb",
"value":1},
{ "key":"skynet",
"value":1},
]
}

30. REDUCE
map: function(doc) {
if (doc.tags && docs.tags.length > 0) {
for (var i = 0; i < doc.tags.length; i++) {
emit(doc.tags[i], "yer ma");
}
}
},
reduce: function (tag, count) {
return sum(tag);
}

31. THEN...

32. BEWARE OF REDUCE VALUES

33. REPLICATION
It fuckin’ rules.

34. REPLICATION
Easy (See later futon ;-))
Continuous... or not :P
Replicates your views
Replicate only what you need (filter?)

35. REPLICATION
curl -X POST http://localhost:5984/_replicate
'{"source":"/dbname", "target": "http://localhost:5555/otherdb", "continuous": true}'

36. REPLICATION
Source The boss Target
changes? watcha
need??
target
needs x, y, z save them

37. REPLICATION
MASTER / SLAVES

38. REPLICATION
MASTER / SLAVES

39. REPLICATION
MULTI MASTER

40. REPLICATION
MULTI MASTER

41. REPLICATION
USE CASE
Automated job
to validate and test data
and do bunch of shits

42. FUTON

43. FUTON

44. NOTE TO SELF.
Show them.
Open up CouchDBX

45. COOL THINGS
Authorization
CouchDB Lucene
Lounge
CouchDBX
Couchio
Cloudant
A bunch of random bits and pieces

46. COMPLETE SHITE COMING UP
eas
r e id
sha
W
le! NO
p
s peo
cus
Dis

47. CONCEPTS AND IDEAS
Graph Theory
...
ss ion
u
a disc
t
d star
tr y an

48. CONCEPTS AND IDEAS
Ghost Replication
...
ss ion
u
a disc
t
d star
tr y an

49. CONCEPTS AND IDEAS
Shared Index Replication
...
ss ion
u
a disc
t
d star
tr y an

50. QUESTIONS?

51. ME! MEEE!!!
@davidcoallier
david@echolibre.com

52. THANKS

53. LINKS
- https://nosqleast.com/2009/slides/miller-couchdb.pdf
- http://couch.io
- http://cloudant.com
- http://wiki.apache.org/couchdb/CouchDB_in_the_wild
- irc://couchdb@freenode.net (Bug jan___ ;-))