我知道 Mongoid v3+ 支持通过 Model.collection.insert() 进行批量插入。但是，我认为它不支持每条记录的属性不同的批量更新(所以我认为 update_all 也不起作用)。有没有办法进行批量更新/更新插入而不是单记录查找和更新？

这是一个简化的示例，其中我有 2 个模型:

class Product
  ...
  has_and_belongs_to_many :lists
end

class List
  ...
  has_and_belongs_to_many :products
end

当一个新的Product被创建时，我将它与一个或多个Lists相关联。但是，我还需要每天更新 Product 属性，而不会丢失 List 引用信息(我认为对 Product 的验证不会运行)。

一种不使用批处理的方法是在 Product 上调用 find_or_initialize_by 并更新属性。但是为 10K-1M+ 记录这样做非常耗时。

另一种使用批量插入的方法是先执行 Product.delete_all，然后执行 Product.collection.insert(...)，但这会创建新的 product_ids 和 List 的关系不再维护。

有没有办法在这个例子中进行批量更新或 upsert？

最佳答案

MongoDB 2.6 支持 update 命令，见 http://docs.mongodb.org/manual/reference/command/update/

Mongoid.default_session 为您提供了在 MongoDB 数据库级别对 command 方法的相应访问权限。 以下示例显示了如何构造和发出批量更新命令来回答您的问题。 输出显示了 10 个列表， 个人与批量更新运行时间的比较， 显示更新的库存计数的产品集合的转储， 以及批量更新命令的结构。 即使在这个简单的演示中，批量更新与单独更新相比也有显着的性能提升。

Ruby 'mongo' 1.x 驱动程序支持用于批量写入的流畅 API， 这也将得到新的 Ruby 'mongo' 2.0 驱动程序的支持，该驱动程序最终将进入 Mongoid。 Mongoid v3+ 当前使用 Moped 驱动程序，它没有用于批量写入的流畅 API。 但正如这里所展示的， 构造并直接发出批量写入(批量更新)命令相当简单 在 Mongoid/Moped 中通过 Session#command 方法。

希望这会有所帮助。

app/models/product.rb

class Product
  include Mongoid::Document
  field :name, type: String
  field :stock, type: Integer, default: 0
  has_and_belongs_to_many :lists, index: true
end

app/models/list.rb

class List
  include Mongoid::Document
  field :name, type: String
  has_and_belongs_to_many :products
end

test/unit/product_test.rb

require 'test_helper'
require 'benchmark'
require 'pp'

class ProductTest < ActiveSupport::TestCase
  def setup
    @session = Mongoid.default_session
    @session.drop
  end
  test '0. mongoid version' do
    puts "\nMongoid::VERSION:#{Mongoid::VERSION}\nMoped::VERSION:#{Moped::VERSION}"
  end
  def individual_updates(list_ids, repetitions)
    repetitions.times do
      list_ids.each_with_index do |list_id, index|
        Product.where(:list_ids => list_id).update_all({'$inc' => {'stock' => index}})
      end
    end
  end
  def bulk_command(list_ids, repetitions)
    updates = []
    repetitions.times do
      list_ids.each_with_index do |list_id, index|
        updates << {'q' => {'list_ids' => list_id}, 'u' => {'$inc' => {'stock' => index}}, 'multi' => true}
      end
    end
    { update: Product.collection_name.to_s, updates: updates, ordered: false }
  end
  def bulk_updates(list_ids, repetitions)
    @session.command(bulk_command(list_ids, repetitions))
  end
  test 'x' do
    puts
    [
      ['ASUS MeMO Pad FHD 10', ['ASUS', 'tablet', 'Android']],
      ['Apple iPad Air Wi-Fi + Cellular 128GB - Silver', ['Apple', 'tablet', 'iOS']],
      ['Apple iPad mini with Retina display Wi-Fi + Cellular 128GB - Silver', ['Apple', 'tablet', 'iOS']],
      ['Apple iPhone 5c 32GB Green', ['Apple', 'phone', 'iOS']],
      ['Apple iPhone 5s 64GB Space Gray', ['Apple', 'phone', 'iOS']],
      ['LG G Pad 8.3 Tablet', ['LG', 'tablet', 'Android']],
      ['LG Google Nexus 5 White', ['LG', 'phone', 'Android']],
      ['Microsoft Surface 7ZR-00001', ['Microsoft', 'tablet', 'Windows 8 RT']],
      ['Samsung Galaxy S4 I9500', ['Samsung', 'phone', 'Android']],
      ['Samsung Galaxy Tab S 8.4', ['Samsung', 'tablet', 'Android']]
    ] .each do |product_name, list_names|
      product = Product.create(name: product_name)
      list_names.each do |list_name|
        list = List.where(name: list_name).first_or_create
        list.products << product
      end
    end
    list_names = List.all.to_a.collect(&:name).sort.uniq
    p list_names
    list_ids = list_names.collect{|list_name| List.where(name: list_name).first.id}
    assert(list_ids.count > 0)

    Benchmark.bm(20) do |x|
      x.report('individual updates') { individual_updates(list_ids, 100) }
      x.report('bulk updates') { bulk_updates(list_ids, 100) }
    end

    pp Product.all.to_a

    db_command = bulk_command(list_ids, 1)
    assert(db_command[:updates].size > 0)
    pp db_command
  end
end

rake 式测试

Run options:

# Running tests:

[1/2] ProductTest#test_0._mongoid_version
Mongoid::VERSION:3.1.6
Moped::VERSION:1.5.2
[2/2] ProductTest#test_x
["ASUS", "Android", "Apple", "LG", "Microsoft", "Samsung", "Windows 8 RT", "iOS", "phone", "tablet"]
                           user     system      total        real
individual updates     0.420000   0.070000   0.490000 (  0.489579)
bulk updates           0.060000   0.000000   0.060000 (  0.180926)
[#<Product _id: 5408b72b7f11bad1ca000001, name: "ASUS MeMO Pad FHD 10", stock: 2000, list_ids: ["5408b72c7f11bad1ca000002", "5408b72c7f11bad1ca000003", "5408b72c7f11bad1ca000004"]>,
 #<Product _id: 5408b72c7f11bad1ca000005, name: "Apple iPad Air Wi-Fi + Cellular 128GB - Silver", stock: 3600, list_ids: ["5408b72c7f11bad1ca000006", "5408b72c7f11bad1ca000003", "5408b72c7f11bad1ca000007"]>,
 #<Product _id: 5408b72c7f11bad1ca000008, name: "Apple iPad mini with Retina display Wi-Fi + Cellular 128GB - Silver", stock: 3600, list_ids: ["5408b72c7f11bad1ca000006", "5408b72c7f11bad1ca000003", "5408b72c7f11bad1ca000007"]>,
 #<Product _id: 5408b72c7f11bad1ca000009, name: "Apple iPhone 5c 32GB Green", stock: 3400, list_ids: ["5408b72c7f11bad1ca000006", "5408b72c7f11bad1ca00000a", "5408b72c7f11bad1ca000007"]>,
 #<Product _id: 5408b72c7f11bad1ca00000b, name: "Apple iPhone 5s 64GB Space Gray", stock: 3400, list_ids: ["5408b72c7f11bad1ca000006", "5408b72c7f11bad1ca00000a", "5408b72c7f11bad1ca000007"]>,
 #<Product _id: 5408b72c7f11bad1ca00000c, name: "LG G Pad 8.3 Tablet", stock: 2600, list_ids: ["5408b72c7f11bad1ca00000d", "5408b72c7f11bad1ca000003", "5408b72c7f11bad1ca000004"]>,
 #<Product _id: 5408b72c7f11bad1ca00000e, name: "LG Google Nexus 5 White", stock: 2400, list_ids: ["5408b72c7f11bad1ca00000d", "5408b72c7f11bad1ca00000a", "5408b72c7f11bad1ca000004"]>,
 #<Product _id: 5408b72c7f11bad1ca00000f, name: "Microsoft Surface 7ZR-00001", stock: 3800, list_ids: ["5408b72c7f11bad1ca000010", "5408b72c7f11bad1ca000003", "5408b72c7f11bad1ca000011"]>,
 #<Product _id: 5408b72c7f11bad1ca000012, name: "Samsung Galaxy S4 I9500", stock: 2800, list_ids: ["5408b72c7f11bad1ca000013", "5408b72c7f11bad1ca00000a", "5408b72c7f11bad1ca000004"]>,
 #<Product _id: 5408b72c7f11bad1ca000014, name: "Samsung Galaxy Tab S 8.4", stock: 3000, list_ids: ["5408b72c7f11bad1ca000013", "5408b72c7f11bad1ca000003", "5408b72c7f11bad1ca000004"]>]
{:update=>"products",
 :updates=>
  [{"q"=>{"list_ids"=>"5408b72c7f11bad1ca000002"},
    "u"=>{"$inc"=>{"stock"=>0}},
    "multi"=>true},
   {"q"=>{"list_ids"=>"5408b72c7f11bad1ca000004"},
    "u"=>{"$inc"=>{"stock"=>1}},
    "multi"=>true},
   {"q"=>{"list_ids"=>"5408b72c7f11bad1ca000006"},
    "u"=>{"$inc"=>{"stock"=>2}},
    "multi"=>true},
   {"q"=>{"list_ids"=>"5408b72c7f11bad1ca00000d"},
    "u"=>{"$inc"=>{"stock"=>3}},
    "multi"=>true},
   {"q"=>{"list_ids"=>"5408b72c7f11bad1ca000010"},
    "u"=>{"$inc"=>{"stock"=>4}},
    "multi"=>true},
   {"q"=>{"list_ids"=>"5408b72c7f11bad1ca000013"},
    "u"=>{"$inc"=>{"stock"=>5}},
    "multi"=>true},
   {"q"=>{"list_ids"=>"5408b72c7f11bad1ca000011"},
    "u"=>{"$inc"=>{"stock"=>6}},
    "multi"=>true},
   {"q"=>{"list_ids"=>"5408b72c7f11bad1ca000007"},
    "u"=>{"$inc"=>{"stock"=>7}},
    "multi"=>true},
   {"q"=>{"list_ids"=>"5408b72c7f11bad1ca00000a"},
    "u"=>{"$inc"=>{"stock"=>8}},
    "multi"=>true},
   {"q"=>{"list_ids"=>"5408b72c7f11bad1ca000003"},
    "u"=>{"$inc"=>{"stock"=>9}},
    "multi"=>true}],
 :ordered=>false}
Finished tests in 1.334821s, 1.4983 tests/s, 1.4983 assertions/s.
2 tests, 2 assertions, 0 failures, 0 errors, 0 skips

https://stackoverflow.com/questions/25550690/