0

Ruby Mongo 驱动程序问题:

如何一次从集合中输出 5_000 个文档批次,直到我读取集合中的最后一个文档而不先将整个数据库转储到内存中?

这对我来说真的很糟糕

mongo = MongoClient.new('localhost', 27017)['sampledb']['samplecoll']
@whois.find.to_a....
4

1 回答 1

1

Mongo::Collection#find 返回一个可枚举的 Mongo::Cursor。对于批处理 Enumerable#each_slice 是您的朋友,非常值得添加到您的工具包中。

希望你喜欢这个。

find_each_slice_test.rb

require 'mongo'
require 'test/unit'

class FindEachSliceTest < Test::Unit::TestCase
  def setup
    @samplecoll = Mongo::MongoClient.new('localhost', 27017)['sampledb']['samplecoll']
    @samplecoll.remove
  end

  def test_find_each_slice
    12345.times{|i| @samplecoll.insert( { i: i } ) }
    slice__max_size = 5000
    @samplecoll.find.each_slice(slice__max_size) do |slice|
      puts "slice.size: #{slice.size}"
      assert(slice__max_size >= slice.size)
    end
  end
end

红宝石 find_each_slice_test.rb

Run options: 

# Running tests:

slice.size: 5000
slice.size: 5000
slice.size: 2345
.

Finished tests in 6.979301s, 0.1433 tests/s, 0.4298 assertions/s.

1 tests, 3 assertions, 0 failures, 0 errors, 0 skips
于 2013-01-31T17:52:25.110 回答