csanz · July 3, 2012 05:46
diff --git a/mongodb.js b/mongodb.js
 var users = []
 db.users.find({}, {_id:1}).limit(15000).forEach(function(data){ users.push(data._id) })
 db.activities.find({'user.id': { $in: users }}).sort({created_at: -1})

 // in less than 2 secs.
	var users = []
	db.users.find({}, {_id:1}).limit(15000).forEach(function(data){ users.push(data._id) })
	db.activities.find({'user.id': { $in: users }}).sort({created_at: -1})

	// in less than 2 secs.