Why You Should Never Use an ORM

Transcript

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

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2. You crazy man...
   

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

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5. Violence
   My Path Of
   

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6. @gem
   

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7. HTTParty
   

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8. HappyMapper
   

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9. MongoMapper
   

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10. ToyStore
    

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12. View Slide

13. Three Points
    

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14. 1) Interface
    Think About Your
    

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15. 1) Interface
    Think About Your
    2) Data
    

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

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17. Your Interface
    Think About
    

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

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

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20. site.add_owner(user)
    

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

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

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23. user.maximize(site)
    

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

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

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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 # ...
    

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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
    

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

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

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30. Your Interface
    Think About
    

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31. Your Data
    Think About
    

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

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33. Failure and Triumph
    A Story of
    

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

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

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36. View Slide

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

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38. View Slide

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

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

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

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42. NewContent.for_site_and_date(site, date)
    

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43. db['c.2011.5']
    

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

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

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46. View Slide

47. /about/
    

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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
    

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

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51. Counts
    Every bit
    

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52. Integers
    

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

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

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

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56. Compression
    

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

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

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

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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
    

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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
    

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62. Partial Updates
    

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63. site.atomic_update_attributes(attrs)
    

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64. Unused Fields
    

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65. Counts
    Where
    

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66. Memory/Disk/Network
    

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

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

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

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

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

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

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73. Go A Long Way
    A Little Ruby Can
    

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74. Move
    

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75. Move
    BigintMove
    

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76. Move
    BigintMove
    MakeYouWannaMove
    

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77. Move
    BigintMove
    MakeYouWannaMove
    DaMove
    

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78. Move
    BigintMove
    MakeYouWannaMove
    DaMove
    SmoothMove
    

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79. Move
    BigintMove
    MakeYouWannaMove
    DaMove
    SmoothMove
    NightMove
    

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80. Move
    BigintMove
    MakeYouWannaMove
    DaMove
    SmoothMove
    NightMove
    DanceMove
    

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

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

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

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84. Your Data
    Think About
    

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85. Your Code
    Think About
    

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86. “
    No code is faster
    than no code.
    

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

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

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

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90. write code
    Don’t be afraid to
    

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91. read code
    Don’t be afraid to
    

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92. fail
    Don’t be afraid to
    

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

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94. Your Code
    Think About
    

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

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96. Ordered List
    Thank you!
    [email protected]
    John Nunemaker
    RailsConf Baltimore, MD
    May 17, 2011
    @jnunemaker
    

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