Why You Should Never Use an ORM

My presentation at RailsConf 2011 on thinking about your interface, your data and your code.

Transcript

1. Ordered List
   @jnunemaker
   RailsConf Baltimore, MD
   May 17, 2011
   Why You Should Never
   Use an ORM
   

   View Slide

2. You crazy man...
   

   View Slide

3. View Slide

4. “
   Albert Einstein
   Any intelligent fool can
   make things bigger, more
   complex, and more
   violent.
   

   View Slide

5. Violence
   My Path Of
   

   View Slide

6. @gem
   

   View Slide

7. HTTParty
   

   View Slide

8. HappyMapper
   

   View Slide

9. MongoMapper
   

   View Slide

10. ToyStore
    

    View Slide

11. View Slide

12. View Slide

13. Three Points
    

    View Slide

14. 1) Interface
    Think About Your
    

    View Slide

15. 1) Interface
    Think About Your
    2) Data
    

    View Slide

16. 1) Interface
    Think About Your
    2) Data
    3) Code
    

    View Slide

17. Your Interface
    Think About
    

    View Slide

18. “
    John Nunemaker
    ORMs too often lead to
    interface laziness.
    

    View Slide

19. site.memberships.create({
    :user_id => user.id,
    :owner => true,
    })
    

    View Slide

20. site.add_owner(user)
    

    View Slide

21. membership.update_attributes({
    :state => 1,
    })
    

    View Slide

22. membership.update_attributes({
    :state => 'maximized',
    })
    

    View Slide

23. user.maximize(site)
    

    View Slide

24. content.to_json({
    'a crap ton': 'of options'
    })
    

    View Slide

25. ContentPresenter.new(site, date, {
    :page => params['page'],
    }).to_json
    

    View Slide

26. class ContentPresenter
    include BasePresenter
    def initialize(site, date, options={})
    @site, @date = site, date
    @options = options
    end
    def page # ...
    def per_page # ...
    def total # ...
    def path # ...
    def prev_path # ...
    def next_path # ...
    def next_page_path # ...
    def prev_page_path # ...
    def paginated # ...
    def content # ...
    

    View Slide

27. def path # ...
    def prev_path # ...
    def next_path # ...
    def next_page_path # ...
    def prev_page_path # ...
    def paginated # ...
    def content # ...
    def as_json(options = nil)
    {
    'date' => @date.to_s,
    'prev_path' => prev_path,
    'next_path' => next_path,
    'content' => content,
    'page' => page,
    'per_page' => per_page,
    'total' => total,
    'prev_page_path' => prev_page_path,
    'next_page_path' => next_page_path,
    }
    end
    end
    

    View Slide

28. Content.paginate({
    :conditions => {
    :site_id => site.id,
    :date => date,
    },
    :page => params['page'],
    :per_page => 15,
    })
    

    View Slide

29. site.content_for_date(date, {
    :page => params['page'],
    })
    

    View Slide

30. Your Interface
    Think About
    

    View Slide

31. Your Data
    Think About
    

    View Slide

32. “
    John Nunemaker
    ORMs sometimes hide
    creative ways you can
    store and retrieve
    your data.
    

    View Slide

33. Failure and Triumph
    A Story of
    

    View Slide

34. {
    '_id' => 'site_id:2011-03-28',
    '/' => {'v' => 200, 't' => 'Home'},
    '/about/' => {'v' => 50, 't' => 'About'},
    '/foo/' => {'v' => 23, 't' => 'Foo!'},
    }
    

    View Slide

35. You say heresy! I say use case...
    

    View Slide

36. View Slide

37. Content.get("#{site.id}:2011-03-28")
    

    View Slide

38. View Slide

39. write data
    ensure_index(site_id, date, path)
    

    View Slide

40. read data
    ensure_index(site_id, date, views)
    

    View Slide

41. {
    '_id' => BSON::ObjectId.new,
    'sid' => site_id,
    'p' => '/about/',
    'd' => '2011-03-28',
    'v' => 50,
    }
    

    View Slide

42. NewContent.for_site_and_date(site, date)
    

    View Slide

43. db['c.2011.5']
    

    View Slide

44. db['c.2011.5']
    read index
    write index
    

    View Slide

45. db['c.2011.4'] => db['c.2011.5']
    read index
    write index
    

    View Slide

46. View Slide

47. /about/
    

    View Slide

48. /this/is/my/really/long/
    and/descriptive/path/and/
    of/course/we/need/to/
    have/a/query/string?
    gibberish=true&yunolikesh
    orturls=false#DontForgetT
    oHashTagIt
    

    View Slide

49. View Slide

50. Zlib.crc32('...really long path...')
    762151429
    

    View Slide

51. Counts
    Every bit
    

    View Slide

52. Integers
    

    View Slide

53. Site.create(:state => 'enabled')
    

    View Slide

54. class Site
    States = {
    'enabled' => 1,
    'disabled' => 2,
    }
    end
    Site.create({
    :state => Site::States['enabled'],
    })
    

    View Slide

55. class Site
    def enabled?
    state == States['enabled']
    end
    def disabled?
    !enabled?
    end
    end
    

    View Slide

56. Compression
    

    View Slide

57. require 'rsmaz'
    compressed = RSmaz.compress(str)
    decompressed = RSmaz.decompress(compressed)
    

    View Slide

58. require 'zlib'
    compressed = Zlib::Deflate.deflate(str)
    decompressed = Zlib::Inflate.inflate(compressed)
    

    View Slide

59. require 'msgpack'
    ids = [1,2,3,4,5,6,7,8,9,10]
    compressed = MessagePack.pack(ids)
    decompressed = MessagePack.unpack(compressed)
    

    View Slide

60. class Stylesheet
    class RSmazCompressor
    def self.compress(str)
    RSmaz.compress(str)
    end
    def self.decompress(str)
    RSmaz.decompress(str)
    end
    end
    class ZlibCompressor
    def self.compress(str)
    Zlib::Deflate.deflate(str)
    end
    def self.decompress(str)
    Zlib::Deflate.inflate(str)
    end
    end
    

    View Slide

61. Compressors = {
    1 => RSmazCompressor,
    2 => ZlibCompressor,
    }
    key :compressor_id, Integer
    key :contents, String
    validates_inclusion_of :compressor_id,
    :within => Compressors.keys
    def contents
    value = read_attribute(:contents)
    compressor.decompress(value)
    end
    def compressor
    Compressors[compressor_id]
    end
    end
    

    View Slide

62. Partial Updates
    

    View Slide

63. site.atomic_update_attributes(attrs)
    

    View Slide

64. Unused Fields
    

    View Slide

65. Counts
    Where
    

    View Slide

66. Memory/Disk/Network
    

    View Slide

67. class SiteMode
    include Scam
    attr_accessor :name
    def password_required?
    id == 2
    end
    def item_cache?
    id == 1
    end
    end
    

    View Slide

68. SiteMode.create({
    :id => 1,
    :name => 'live'
    })
    SiteMode.all
    # find by id or string id
    pp SiteMode.find(2)
    pp SiteMode.find('2')
    

    View Slide

69. class Plan
    include Toy::Store
    store(:memory, {})
    attribute(:title, String)
    attribute(:price, Integer)
    end
    

    View Slide

70. class Asset
    plugin Joint
    attachment :file
    def page_cache(version=nil)
    page_cache_original
    page_cache_version(version)
    end
    end
    

    View Slide

71. current_user.sites.map do |site|
    Site.get(site['id'])
    end
    

    View Slide

72. ids = current_user.sites.map do |site|
    site['id']
    end
    Site.all(:_id.in => ids)
    

    View Slide

73. Go A Long Way
    A Little Ruby Can
    

    View Slide

74. Move
    

    View Slide

75. Move
    BigintMove
    

    View Slide

76. Move
    BigintMove
    MakeYouWannaMove
    

    View Slide

77. Move
    BigintMove
    MakeYouWannaMove
    DaMove
    

    View Slide

78. Move
    BigintMove
    MakeYouWannaMove
    DaMove
    SmoothMove
    

    View Slide

79. Move
    BigintMove
    MakeYouWannaMove
    DaMove
    SmoothMove
    NightMove
    

    View Slide

80. Move
    BigintMove
    MakeYouWannaMove
    DaMove
    SmoothMove
    NightMove
    DanceMove
    

    View Slide

81. Partition.create({
    :association => :moves,
    :model => Move,
    :first_id => 1,
    :writer => false,
    })
    

    View Slide

82. Partition.for_writes.model.create(...)
    

    View Slide

83. Partition.since(since_id, last_move_id).map do |p|
    send(p.association).since(since_id)
    end
    

    View Slide

84. Your Data
    Think About
    

    View Slide

85. Your Code
    Think About
    

    View Slide

86. “
    No code is faster
    than no code.
    

    View Slide

87. $ bx ruby performance/reads.rb
    Collection#find_one
    0.270231008529663
    Site.first
    0.69925594329834
    

    View Slide

88. /track - no
    /content - no
    /referrers - no
    /sites - yes
    /users - yes
    

    View Slide

89. class Hit
    def site
    @site ||= begin
    query = {'_id' => site_id}
    options = {:fields => ['tz']}
    collection.find_one(query, options)
    end
    end
    end
    

    View Slide

90. write code
    Don’t be afraid to
    

    View Slide

91. read code
    Don’t be afraid to
    

    View Slide

92. fail
    Don’t be afraid to
    

    View Slide

93. Site.find(id)
    Site.create({
    :title => 'RailsTips',
    })
    site.update_attributes(attrs)
    site.to_json
    

    View Slide

94. Your Code
    Think About
    

    View Slide

95. “
    Albert Einstein
    It takes a touch of genius
    —and a lot of courage—to
    move in the opposite
    direction.
    

    View Slide

96. Ordered List
    Thank you!
    john@orderedlist.com
    John Nunemaker
    RailsConf Baltimore, MD
    May 17, 2011
    @jnunemaker
    

    View Slide