Mongodb Randomizer Script

randomizer.js

db.users.find().forEach(function(user) { 
  db.users.update({_id: user._id}, { $set: { random: Math.random() }});
});

// Runs in less than 1 sec for 2k records

db.users.ensureIndex({random:1});

/*

This also runs in less than 1 sec for 2k records

db.users.find({},{screen_name:1}).limit(5).sort({random: 1})
{ "_id" : ObjectId("4e1aa2377dc6f70100000af3"), "screen_name" : "sadatrahman" }
{ "_id" : ObjectId("4e0ffce49577900100000210"), "screen_name" : "chrisdickinson" }
{ "_id" : ObjectId("4e1a95487dc6f701000005eb"), "screen_name" : "jspepper" }
{ "_id" : ObjectId("4e13934156a8ef01000026de"), "screen_name" : "mcavage" }
{ "_id" : ObjectId("4e174b9387833b01000027f6"), "screen_name" : "DariuszDZW" }

(run the update script above again)

db.users.find({},{screen_name:1}).limit(5).sort({random: 1})
{ "_id" : ObjectId("4e14e3284977db01000002ec"), "screen_name" : "tkousky" }
{ "_id" : ObjectId("4e10144a9577900100000dbe"), "screen_name" : "nico" }
{ "_id" : ObjectId("4e1b1a6e6fed2f0100000bb1"), "screen_name" : "snarkie" }
{ "_id" : ObjectId("4e1aa69e7dc6f70100000ccd"), "screen_name" : "tonyarnold" }
{ "_id" : ObjectId("4e1a977a7dc6f70100000657"), "screen_name" : "jamie" }


*/

Hells yes!