Files used to benchmark MongoDB random document in a collection.

method1_prepare.js

// Preparation for method 1
use benchmark;

print("Method 1, preparation start.");

db.col.ensureIndex( { random_point: '2d' } );

// This feels ugly...
db.col.find().map(function(u) {
	db.col.update(
		{ _id: u._id },
		{ $set: { random_point: [ Math.random(), 0 ] } }
	); 
});

print("Method 1, preparation end.");

method1_run.js

// Run for method 1
use benchmark;

var N = 10000;

var start_date = new Date();

for (var i = 0; i < N; i++) {
	db.col.findOne({random_point : { $near : [ Math.random(), 0 ] } } );
}

var end_date = new Date();

print("Method 1, run time for ", N, " picks: ", (end_date - start_date), " ms");

method2_prepare.js

// Preparation for method 2
use benchmark;

print("Method 2, preparation start.");

// This feels ugly...
db.col.find().map(function(u) {
	db.col.update(
		{ _id: u._id },
		{ $set: { random_point: Math.random() } }
	); 
});

print("Method 2, preparation end.");

method2_run.js

// Run for method 2
use benchmark;

var N = 10000;

var start_date = new Date();

for (var i = 0; i < N; i++) {
	db.col.findOne({random_point : { $gte : Math.random() } } );
}

var end_date = new Date();

print("Method 2, run time for ", N, " picks: ", (end_date - start_date), " ms");

method3_run.js

// Run for method 3
use benchmark;

var N = 10000;

function random_id(obj_id_slice1, obj_id_slice2, count) {
	var v = obj_id_slice2 + Math.floor(Math.random() * (count + 1));
	return ObjectId(obj_id_slice1 + v.toString(16));
}

var count = db.col.count();
var first_obj_id = db.col.find().sort({ _id: 1 }).limit(1)[0]._id.valueOf();

var first_obj_id_slice1 = first_obj_id.slice(0, 11);
var first_obj_id_slice2 = parseInt(first_obj_id.slice(11, 24), 16);

var start_date = new Date();

for (var i = 0; i < N; i++) {
	db.col.findOne({ _id: { $gte: random_id(first_obj_id_slice1, first_obj_id_slice2, count) } });
}

var end_date = new Date();

print("Method 3, run time for ", N, " picks: ", (end_date - start_date), " ms");

method4a_run.js

// Run for method 4a
use benchmark;

var N = 10000;

var start_date = new Date();

for (var i = 0; i < N; i++) {
	db.col.find().limit(-1).skip(Math.random() * db.col.count());
}

var end_date = new Date();

print("Method 4a, run time for ", N, " picks: ", (end_date - start_date), " ms");

method4b_run.js

// Run for method 4b
use benchmark;

var N = 10000;
var nb = db.col.count();

var start_date = new Date();

for (var i = 0; i < N; i++) {
	db.col.find().limit(-1).skip(Math.random() * nb);
}

var end_date = new Date();

print("Method 4b, run time for ", N, " picks: ", (end_date - start_date), " ms");