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Memory usage for MongoMapper' where query
# load_test_books.rb
require 'rubygems'
require 'mongo_mapper'
MongoMapper.connection = Mongo::Connection.new('127.0.0.1', 27017)
MongoMapper.database = 'dpu-test'
class Book
include MongoMapper::Document
key :name, String
key :price, Integer
key :category, String
end
def load_test_books(nums = 100 * 100 * 10)
nums.times do |num|
Book.create(:price => rand(50) + 20, :name => "Ruby##{num+1}", :category => 'ruby')
end
end
# load 100,000 books
load_test_books
# query_where_all.rb
p Book.count
before_memory_usage = `ps -o rss= -p #{$$}`.to_i
Book.where(:category => 'ruby').all
after_memory_usage = `ps -o rss= -p #{$$}`.to_i
p 'memory usage before sum book price:'
p before_memory_usage
p 'memory usage after sum book price:'
p after_memory_usage
p after_memory_usage - before_memory_usage #in my computer printed 234.8m
# query_where.rb
p Book.count
before_memory_usage = `ps -o rss= -p #{$$}`.to_i
Book.where(:category => 'ruby')
after_memory_usage = `ps -o rss= -p #{$$}`.to_i
p 'memory usage before sum book price:'
p before_memory_usage
p 'memory usage after sum book price:'
p after_memory_usage
p after_memory_usage - before_memory_usage #in my computer only print 4kb
# paginate_where.rb
p Book.count
before_memory_usage = `ps -o rss= -p #{$$}`.to_i
total_price = 0
books = Book.where(:category => 'ruby')
pages = books.count / 100 + 1
1.upto pages do |page|
Book.where(:category => 'ruby').paginate(:page => page, :per_page => 100).each { |book| total_price += book.price }
end
after_memory_usage = `ps -o rss= -p #{$$}`.to_i
p 'memory usage before sum book price:'
p before_memory_usage
p 'memory usage after sum book price:'
p after_memory_usage
p after_memory_usage - before_memory_usage # print 28kb in my computer
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