1. MongoDB Forward Tech Away Day 24 Sep 2010
toni@forward.co.uk
Monday, 27 September 2010

2. 1
Get to know
MongoDB
Monday, 27 September 2010

3. try.mongodb.org
Monday, 27 September 2010

4. Ruby driver
require 'rubygems'
require 'mongo'
@db = Mongo::Connection.new.db("blog")
@blogposts = @db['blogposts']
Monday, 27 September 2010

5. a simple document
post = {
:time => Time.now.utc,
:title => "Simple Post",
}
@blogposts << blogpost
Monday, 27 September 2010

6. When we call #save:
1. Adds an _id
2. Serialise to BSON
3. socket.send()
Monday, 27 September 2010

7. 2
Use rich
documents
Monday, 27 September 2010

8. “complex objects”
blogpost = {
:title => "My First Post",
:author => {:name => "Jane"},
:comments => [{ :by => "Abe", :text => "First" },
{ :by => "Ada", :text => "Good post" }]
}
@blogposts.save(blogpost)
Monday, 27 September 2010

9. “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)
Monday, 27 September 2010

10. dynamic queries
@blogposts.find( { "author.name" => "Jane" } )
@blogposts.find( { "author.name" => /^J/ } )
@blogposts.find( { :time =>
{'$lte' => Time.utc(1970,1,1)} } )
@blogposts.find( { :languages => {'$in' =>
["English", "Italian"] } } )
Monday, 27 September 2010

11. find and modify!
cmd = BSON::OrderedHash.new
cmd[:findandmodify] = 'blogposts'
cmd[:query] = { :title => "My First Post" }
cmd[:update] = { '$set' =>
{ :title => "My First Post updated"}}
DB.command(cmd)
Monday, 27 September 2010

12. upsert
@blogposts.update({:title => "My First Post"}, blogpost,
{ :upsert => true })
Monday, 27 September 2010

13. update
@blogposts.update({:title => "My First Post"}, blogpost)
@blogposts.update(
{:title => "My First Post"}, {'$inc' => {"views" => 1}})
Monday, 27 September 2010

14. query operators
"$ne" "$inc"
"$in" "$set"
"$nin" "$push"
"$mod" "$pushAll"
"$all" "$pop"
"$size" "$pull"
"$exists" "$pullAll"
Monday, 27 September 2010

15. 3
Map reduce for
aggregation
Monday, 27 September 2010

16. 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
Monday, 27 September 2010

17. 4
Indexes are
indexes
Monday, 27 September 2010

18. indexes
@blogposts.create_index([[ "comments.by" , Mongo::ASCENDING ]]);
db.blogposts.ensureIndex( { "comments.by" : 1 } );
@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 ]]);
Monday, 27 September 2010

19. 5
GridFS
Monday, 27 September 2010

20. api
grid = Mongo::Grid.new(DB)
my_avatar = File.open('toni.jpg','r')
id = grid.put(my_avatar)
files collection for metadata
chunks collection for data
Monday, 27 September 2010

21. 6
Replication
Monday, 27 September 2010

22. 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.
Monday, 27 September 2010

23. replica sets (1.6+)
• Supports 1-7 servers in the cluster
• Automatic failover
• Automatic recovery
Monday, 27 September 2010

24. 7
Auto-shard
Monday, 27 September 2010

25. mongo shards
Sharding occurs on a per-collection basis
Monday, 27 September 2010

26. 8
Pro & Cons
Monday, 27 September 2010

27. pro & cons
• schema free > no migrations needed
• no sql
• update existing data
• stable
• very nice api
Monday, 27 September 2010

28. good for
• the web
• real time
• logging
• analytics
• humans
Monday, 27 September 2010

29. 9
Links
Monday, 27 September 2010

30. links
• http://api.mongodb.org/ruby/1.0.9/
index.html
• http://www.mongodb.org/
• http://mongoid.org/
Monday, 27 September 2010

31. 10
Questions
Monday, 27 September 2010