Mongo db

MongoDBForward Tech Away Day 24 Sep 2010

[email protected]

Monday, 27 September 2010

1Get to know MongoDB


try.mongodb.org


Ruby driverrequire 'rubygems'require 'mongo'

@db = Mongo::Connection.new.db("blog")

@blogposts = @db['blogposts']


a simple document

post = { :time => Time.now.utc, :title => "Simple Post",}

@blogposts << blogpost


When we call #save:

1. Adds an _id 2. Serialise to BSON 3. socket.send()


2Use rich documents


blogpost = { :title => "My First Post", :author => {:name => "Jane"}, :comments => [{ :by => "Abe", :text => "First" }, { :by => "Ada", :text => "Good post" }]}

@blogposts.save(blogpost)

“complex objects”


blogpost = { :title => "My First Post", :time => Time.now.utc, :author => {:name => "Jane"}, :views => 0, :languages => ["English", "Italian", "Spanish"],

:comments => [{ :by => "Abe", :text => "First", :vote => 1, :date => Time.now.utc }]

}

@blogposts.save(blogpost)

“complex objects”


dynamic [email protected]( { "author.name" => "Jane" } )

@blogposts.find( { "author.name" => /^J/ } )

@blogposts.find( { :time => {'$lte' => Time.utc(1970,1,1)} } )

@blogposts.find( { :languages => {'$in' =>["English", "Italian"] } } )


find and modify!cmd = BSON::OrderedHash.newcmd[:findandmodify] = 'blogposts'cmd[:query] = { :title => "My First Post" }cmd[:update] = { '$set' =>

{ :title => "My First Post updated"}}DB.command(cmd)


upsert

@blogposts.update({:title => "My First Post"}, blogpost, { :upsert => true })


update

@blogposts.update({:title => "My First Post"}, blogpost)

@blogposts.update({:title => "My First Post"}, {'$inc' => {"views" => 1}})


query operators

"$ne""$in""$nin""$mod""$all""$size""$exists"

"$inc""$set""$push""$pushAll" "$pop""$pull""$pullAll"


3Map reduce for aggregation


map reduce def self.target_for_report(report) collections = DB['targets'].group(['metric'], { :report_type => report.report_type,

:project_name => report.project }, { 'docs' => [] }, "function(doc, prev) { prev.docs.push(doc); }"); end


4Indexes are indexes


indexes

db.blogposts.ensureIndex( { "comments.by" : 1 } );

@blogposts.create_index([[ "comments.by" , Mongo::ASCENDING ]]);

@blogposts.create_index([[ :languages , Mongo::ASCENDING ]]);

@blogposts.create_index([[ :time , Mongo::DESCENDING ]]);

@blogposts.create_index([[ :author , Mongo::ASCENDING, true ]]);

@blogposts.create_index([[ "comments.vote" , 1,], [ "comments.date", -1 ]]);


5GridFS


api

files collection for metadatachunks collection for data

grid = Mongo::Grid.new(DB)my_avatar = File.open('toni.jpg','r')id = grid.put(my_avatar)


6Replication


m/s vs replica set

asynchronous replication of data between servers for failover and redundancy

only one server (in the set/shard) is active for writes (the primary, or master) at a given time.


replica sets (1.6+)

• Supports 1-7 servers in the cluster

• Automatic failover

• Automatic recovery


7Auto-shard


mongo shards

Sharding occurs on a per-collection basis


8Pro & Cons


pro & cons

• schema free > no migrations needed

• no sql

• update existing data

• stable

• very nice api


good for

• the web

• real time

• logging

• analytics

• humans


9Links


links

• http://api.mongodb.org/ruby/1.0.9/index.html

• http://www.mongodb.org/

• http://mongoid.org/


http://api.mongodb.org/ruby/1.0.9/index.html




http://www.mongodb.org/

http://www.mongodb.org/

http://mongoid.org/

http://mongoid.org/

10Questions


Mongo db

Documents

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