latinoware

base de dados orientada a

documentos para aplicações Web

Kristina Chodorow

Who am I?

Software Engineer at

Here from New York City

Why Use

Non-Relational DBs?

CAP

• Consistency

• Availability

• Partitioning

nome : "joe" nome : "joe"

Key-Value Stores

Key Value

foo bar

x 123

ts 6:13:26 12/3/1945

data \x9F\x44\x1e

Tokyo Cabinet, Dynamo, MemcacheDB

Key-Value Stores

•Fast

•Simple•Too simple

Column-Oriented

Cassandra

Document-Oriented

{

date : Date(2007-05-07),

time : {

start : 9.25,

end : 10.25

}

sum : 0,

comments : ["task 1", "run 4", "testing module"]

}

vs.

Consistency

Availability

Partitioning

master

slave

Consistency

Availability

Partitioning

slave

Consistency

Availability

Partitioning

master

Consistency

Availability

Partitioning

master

slave

Consistency

Availability

Partitioning

Router

Pair

Pair

Pair

Consistency

Availability

Partitioning

...eventual consistency

Introduction to MongoDB

A JavaScript Database

$ mongodb-linux-1.0/bin/mongo

MongoDB shell version: 1.0.0

url: test

connecting to: test

type "help" for help

>

JSON and BSONStrict JSON types:

{

x : null, y : true, z : 123, w : "xyz",

a : { b : 1 }, c : [1, 2, 3]

}

Mongo JSON adds:

{

ts : new Date(),

query : /regex/ig,

_id : new ObjectId()

}

Collections, not Tables

Collections

{

date : Date(2007-05-07),

time : {

start : 9.25,

end : 10.25

}

sum : 0,

comments : ["task 1", "run 4"]

}

Using the Shell

> db

test

> use xyz

> db

xyz

> db.splorch.find()

>

Inserting

> db.foo.insert({name : "Joe", age : 34})

> db.foo.find({name : "Joe"})

{

"_id" :

ObjectId("2fe3e4d892aa73234c910bed"),

"name" : "Joe",

"age" : 34

}

Object Idsan autogenerated primary key

"_id" : ObjectId("2fe3e4d892aa73234c910bed")

12 bytes:

2fe3e4d892aa73234c910bed

|------||----||--||----|

ts mac pid inc

Nested Objects

> db.blog.insert({title : "First Post",

content : "Hello, world!",

author : {name : "Joe", id : 123},

comments : []

})

Querying

posts = db.blog.find({

"author" : "Joe"})

commentsByFred = db.blog.find({

"comments.author" : "Fred"})

commentedByFred = db.blog.find({

"comments.author" : /fred/i})

Speaking of indexing…

db.people.ensureIndex({"age" : 1});

db.people.ensureIndex({

"name" : -1,

"ts" : -1,

"comments.author" : 1

});

Updating

db.blog.update({title : "First Post"}, {

$push : {

comments : {

author : "Fred",

comment : "Dumb post."

}

}

});

…which gives us:

> db.blog.findOne()

{

_id : ObjectId("4ae06192213900000000745c"),

"title" : "First Post",

"content" : "Hello, world!"

"author" : {"name" : "Joe", "id" : 123}

"comments" : [{

"author" : "Fred",

"comment" : "Dumb post"

}]

}

$ instead of >, <, =, etc.

$gt, $gte, $lt, $lte, $eq, $neq, $exists,

$set, $mod, $where, $in, $nin, $inc

$push, $pull, $pop, $pushAll, $popAll

db.foo.bar.find({x : {$gt : 4}})

$where

db.blog.findOne({$where :

'this.y == (this.x + this.z)'});

Will work:

{"x" : 1, "y" : 4, "z" : 3}

{"x" : "hi", "y" : "hibye", "z" : "bye"}

Won’t work:

{"x" : 1, "y" : 1}

Optimizing $where

db.blogs.findOne({

name : "Sally",

age : {'$gt' : 18},

$where : 'Array.sort(this.interests)[2]

== "volleyball"'});

Cursors

cursor = db.blah.find(array("foo" : "bar"))

while (cursor.hasNext()) {

obj = cursor.next()

}

Applications

Dextify2

FetLife

soliMAP

@trackmeet

Paging

cursor = db.results.find()

.sort({"ts" : -1})

.skip(page_num * results_per_page)

.limit(results_per_page);

Logging

• insert/update/remove is fast

• Capped collections

• Schemaless

• $inc for counts

Storing Files

Max: 4Mb

Storing Files

(More than 4 Mb)

Storing Files

chunks

JJ J

J

JJ

J

J

J

J_id :files

Storing Files

ObjectId fileId = new ObjectId();

fileObj = {

_id : fileId,

filename : "ggbridge.png",

user : "joe",

takenIn : "San Francisco"

}

chunkObj = {

fileId : fileId,

chunkNum : N

data : <binary data>

}

Aggregation

group =~ GROUP BY

Map/Reducedb.runCommand({

mapreduce : <collection>,

map : <mapfunction>,

reduce : <reducefunction>

[, query : <query filter object>]

[, out : <outputcollectionname>]

[, keeptemp: <true|false>]

[, finalize : <finalizefunction>]

})

www.mongodb.org

Drivers

C#, Erlang, Factor

Thank you!

kristina@10gen.com

@kchodorow

@mongodb

irc.freenode.net#mongodb

www.mongodb.org