This document discusses using Riak, a distributed key-value database, with Node.js. Riak uses HTTP as its interface and can store JSON data, making it a good fit for Node.js applications. The Riak client library for Node.js allows storing, retrieving, and querying data from Riak directly in JavaScript code. MapReduce queries in Riak can be used to process large datasets in parallel across the distributed cluster, and custom map and reduce functions can be defined in JavaScript.

1. Riak and Node.js: Best
served with HTTP
Philipp Fehre https://github.com/sideshowcoder

3. What is Riak?
A Key Value store
A Dynamo store!

4. Distributed

7. Replicated

9. Fault tolerant

13. Scaling
Basically means add more machines

14. Gains
more storage
more throughput
lower latency

15. And it is Web friendly
HTTP Interface
Value is irrelevant so you can store JSON
Support for JavaScript functions

16. When to use Riak

18. Data Organization
keys identify objects
objects have metadata
objects are grouped into buckets

19. More Data Features
Links
Secoundary indexes
Timeouts

20. HTTP
Riak understands simple HTTP

21. Create some data
curl -v -XPUT http://localhost:8098/riak/test/doc
-H "Content-Type: application/json"
-d '{"bar":"baz"}'

22. Query by key
curl -v http://localhost:8098/riak/test/doc

23. Everything can be done
via HTTP

24. like setting properties of
the bucket
curl -v -XPUT -H "Content-Type: application/json"
-d '{"props":{"n_val":5}}'

25. or MapReduce
curl -XPOST http://localhost:8098/mapred
-H 'Content-Type: application/json'
-d '{ "inputs":"training",
"query":[{"map":{"language":"javascript",
"source":"function(riakObject) {
var val = riakObject.values[0].data.match(/pizza/g);
return [[riakObject.key, (val ? val.length : 0)]];
}"}}]}'

26. Ok but we do JavaScript

27. ... or more like Node

28. Using Riak from Node

29. JavaScript all the way
down
if you want it to be!

30. The Client
var db = require("riak-js").getClient()

31. Store an Object
var obj = { val: "foo", bar: true }
db.save("foos", "foo_1", obj, {}, function(err) {
if(!err) console.log("stored")
})

32. Retrieve an Object
db.get("foos", "foo_1", function(err, data, meta) {
if(!err) {
console.log(data)
console.log(meta)
}
})

33. Map and Reduce
"MapReduce is a programming model for processing large data
sets with a parallel, distributed algorithm on a cluster" -Wikipedia

35. Riak MapReduce Queries
provide a set of keys
provide a map function
provide a reduce function

36. Select Keys
db.mapreduce.add("foos")

37. var key_filter = [["tokenize", "_", 1],
["to_lower"],
["matches", "foo"]]
db.mapreduce.add({ bucket: "foos", key_filters: key_filter })

38. Map a buildin
db.mapreduce
.add("foos")
.map({ name: 'Riak.mapValueJson', keep: true })
.run()

39. Map custom function
var func = function(v, _keyData, arg) {
var v = Riak.mapValuesJson(v)[0];
(v.val === "foo") ? return [v] : return [];
}
db.mapreduce.add("foos").map(func).run()

40. Reduce with custom
var func = function(values) {
return [ values.length ]
}
db.mapreduce...
.reduce(func)
.run()

41. A little more complex
function(values) {
return values.reduce(function(acc, v) {
if(v.bar) {
var curr = acc["bar"] || 0
acc["bar"] = curr + 1
}
return acc;
})
}

42. Questions
· Usergroup: www.meetup.com/Riak-Munchen/
· More on the basics: littleriakbook.com