Benchmarking retrieving/sorting results from MongoDB

output.txt

With 115k results:

Rehearsal ----------------------------------------------------------------------
sorting Mongo query in Mongo         0.990000   0.100000   1.090000 (  2.193201)
sorting Mongo query in Ruby          0.980000   0.030000   1.010000 (  1.171781)
sorting Postgres query in Postgres   0.100000   0.020000   0.120000 (  2.143469)
sorting Postgres query in Ruby       0.340000   0.030000   0.370000 (  0.485265)
------------------------------------------------------------- total: 2.590000sec

                                         user     system      total        real
sorting Mongo query in Mongo         0.900000   0.040000   0.940000 (  2.101531)
sorting Mongo query in Ruby          0.880000   0.010000   0.890000 (  1.076933)
sorting Postgres query in Postgres   0.090000   0.010000   0.100000 (  2.197068)
sorting Postgres query in Ruby       0.250000   0.010000   0.260000 (  0.372697)

retrieve_sort.rb

# The `people` collection is 1M objects with `name` and `dob` keys, generated with the following call:
# people = 1_000_000.times.map { |i| { name: i.to_s, dob: Time.now - i } }

# Both the MongoDB and Postgres examples have indexes on name and dob as well as an index containing both.

require 'benchmark'
require 'moped'
require 'pg'

mongo = Moped::Session.new(['localhost:27017'])
mongo.use 'test'
collection = mongo[:people]
mongo_query = collection.find(
  '$or' => [
    { name: { '$gt'=>'900000'} },
    { dob: { '$gt' => (Time.now - 100) } }
  ]
)

pg = PG.connect dbname: 'test'
pg_query = %Q{SELECT * FROM people WHERE name > '900000' OR dob > '2013-10-1'::date}

results = { mongo: {}, pg: {} }

Benchmark.bmbm do |x|
  x.report 'sorting Mongo query in Mongo' do
    results[:mongo_mongo] = mongo_query.dup.sort(name: 1).to_a
  end
  x.report 'sorting Mongo query in Ruby' do
    results[:mongo_ruby] = mongo_query.dup.to_a.sort_by { |person| person['name'] }
  end
  x.report 'sorting Postgres query in Postgres' do
    results[:pg_pg] = pg.exec(pg_query + ' ORDER BY name').to_a
  end
  x.report 'sorting Postgres query in Ruby' do
    results[:pg_ruby] = pg.exec(pg_query).to_a.sort_by { |person| person['name'] }
  end
end

# Verify that both queries return the exact same results
raise 'mongo' unless results[:mongo_mongo] == results[:mongo_ruby]
raise 'postgres' unless results[:pg_pg] == results[:pg_ruby]