Short introduction on CouchDB database

1. Introduction to CouchDB
By Bogdan Sabau, SoftVision

2. INTRODUCTION

3. Databases

4. Databases
Relational

5. Databases
Object oriented

6. Databases
Graph

7. Databases
Key-Value based

8. Databases
Document based

9. WHAT IS COUCHDB?

10. • A scalable, fault-tolerant, and schema-free
document-oriented database
• A RESTful HTTP/JSON API accessible from
many programming libraries and tools
• Incremental Map/Reduce queries written in
any language (JavaScript support built-in)
• Incremental and flexible replication with
conflict management

11. SCHEMA FREE DOCUMENT

12. What does it means?
• It means that you don’t need to think to much
upfront about what your data will be
structured like. You don’t need to think about
relations or what might be needed for the
future. You just put the data as it currently is
into the database and in case it changes, you
just change the documents.

13. Relational model
id firstName lastName
1 Danila Prepeleac
2 Gheorghe Doja
customerId phoneTypeId phoneNumber
1 1 004075123321
1 2 064500100
2 1 +4072600300
Customers
Phones
id Type
1 Mobile
2 Home
PhoneTypes

14. Document based
{
"_id":"1",
"_rev":"1c7762a779effe1398d8d2ea36ff958a6",
"firstName":"Gheorghe",
"lastName":"Doja",
"phones":
{
"mobile":"004075123321",
"home":"064500100„
}
}

15. Document based
{
"_id":"1",
"_rev":"1c7762a779effe1398d8d2ea36ff958a6",
"firstName":"Gheorghe",
"lastName":"Doja",
"phones":
{
"mobile":"004075123321",
"home":"064500100„
}
}
Key, unique, it can me
autogenerated (UUID) or the
user can give it

16. Document based
{
"_id":"1",
"_rev":"1c7762a779effe1398d8d2ea36ff958a6",
"firstName":"Gheorghe",
"lastName":"Doja",
"phones":
{
"mobile":"004075123321",
"home":"064500100„
}
}
Key, unique, it can me
autogenerated (UUID) or the
user can give it
Revision number. Yes! It has
revisions!

17. CRUD OPERATIONS

18. CRUD Operations
• CouchDB speaks the language of the web:
REST, HTTP, and JSON are how CouchDB works
natively
• Calls are made to the database via HTTP (we
can use anything that talks HTTP)
• Responses come back as JSON

19. Create database:
bash$ curl -X PUT http://localhost:5984/contacts
{"ok":true}
bash$ curl -X PUT http://localhost:5984/contacts/1 -d
'{"firstName":"Gheorghe","lastName":"Doja","phones":{"mobile":"004075123321","home":"4500100"}}'
{"ok":true,"id":"1","rev":"1-c7762a779effe1398d8d2ea36ff958a6"}
bash$ curl -X GET http://localhost:5984/contacts/_all_docs
{"total_rows":1,"offset":0,"rows":[
{"id":"1","key":"1","value":{"rev":"1-c7762a779effe1398d8d2ea36ff958a6"}}
]}
Get all documents from a database
bash$ curl -X GET http://localhost:5984/contacts/1
{"_id":"1","_rev":"1-
c7762a779effe1398d8d2ea36ff958a6","firstName":"Gheorghe","lastName":"Doja","phones":{"mobile":"004075123321","home":"064500100
"}}
Get a specific document
bash$ curl -X PUT http://localhost:5984/contacts/1 -d '{"_id":"1","_rev":"1-c7762a779effe1398d8d2ea36ff958a6","firstName":"Gheorgh
e","lastName":"Doja","phones":{"mobile":"004075123000","home":"+4064500100"}}‘
{"ok":true,"id":"1","rev":"2-875f4f380fe5e3eeb5fbaeb495fc3599"}
Updates a document
bash$ curl -X DELETE http://localhost:5984/contacts/1?rev="2-875f4f380fe5e3eeb5fbaeb495fc3599"
{"ok":true,"id":"1","rev":"3-de88253ac3cb9463aac609d5fdfd3135"}
Delete a document
Create a new document:

20. Updating documents
• Highly concurent
• It can serve a high number of parallel
requests.
• MVCC (Multiversion concurrency control)

21. Updating a document
_rev: 1
CouchDB

22. Updating a document
_rev: 1
CouchDB
_rev: 1_rev: 1
DerpDerpina

23. Updating a document
_rev: 1
CouchDB
_rev: 1_rev: 1
DerpDerpina

24. Updating a document
_rev: 1
CouchDB
_rev: 1_rev: 1
DerpDerpina

25. Updating a document
_rev: 2
CouchDB
_rev: 1
Derpina

26. Updating a document
_rev: 2
CouchDB
_rev: 1
Derpina

27. Updating a document
_rev: 2
CouchDB
_rev: 1
Derpina

28. Updating a document
_rev: 2
CouchDB
_rev: 1
Derpina

29. Updating a document
_rev: 2
CouchDB
_rev: 1
Derpina
_rev: 2
Derpina

30. Updating a document
_rev: 2
CouchDB
_rev: 2
Derpina

31. Updating a document
_rev: 2
CouchDB
_rev: 2
Derpina

32. Updating a document
_rev: 3
CouchDB

34. MAP/REDUCE FUNCTIONS

36. Views
• Are stored as an accessible web resource on
disk and incrementally updated as well as
replicated with the database
• Each view defines a map function, and can
define a reduce function

37. One simple view
function(doc) {
if (doc.ocupation == "domnitor") {
emit(doc.ocupation, doc.firstName + ' ' + doc.lastName);
}
}
input
output
key value

38. {
_id: "534ce91c445da85f636284856c000c77",
_rev: "1-36d8948a4dc06aad20dfc9a95ad12de1",
firstName: "Bogdan",
lastName: "Sabau",
ocupation: "sportiv"
}
{
_id: "534ce91c445da85f636284856c001087",
_rev: "2-eb737c5882c8e7e351a4f19678eeb9f7",
firstName: "Gheorghe",
lastName: "Doja",
ocupation: "nobil"
}
{
_id: "534ce91c445da85f636284856c001c49",
_rev: "1-35972e6ee7c7ab828d4110c3dbc3a4de",
firstName: "Iacob",
lastName: "Heraclide",
ocupation: "domnitor"
}
{
_id: "534ce91c445da85f636284856c001eb2",
_rev: "1-91c5e4f0cc0836b5f4d0e4bcf3d66467",
firstName: "Alexandru",
lastName: "Lapusneanu",
ocupation: "domnitor"
}
{
_id: "534ce91c445da85f636284856c002529",
_rev: "1-a58e090b6138abf648eb65cbcd077ed7",
firstName: "Constantin",
lastName: "Karadja",
ocupation: "diplomat"
}

39. Output in Futon

40. Reduce function

41. Reduce function

42. REPLICATION

43. Replication
• Peer to peer
• Online/Offline
• Conflict detection and resolution
• Any number of nodes

44. Unidirectional

45. Bidirectional

46. Continuous
8

47. Filtered
Filter
function

48. QUESTIONS?