MongoDB: how to find 10 random document in a collection of 100?

Question

Is MongoDB capable of funding number of random documents without making multiple queries?

e.g. I implemented on the JS side after loading all the document in the col

Answer 1

Here is what I came up in the end:

var numberOfItems = 10;


// GET LIST OF ALL ID's
SchemaNameHere.find({}, { '_id': 1 }, function(err, data) {

    if (err) res.send(err);

    // shuffle array, as per here  https://github.com/coolaj86/knuth-shuffle
    var arr = shuffle(data.slice(0));

    // get only the first numberOfItems of the shuffled array
    arr.splice(numberOfItems, arr.length - numberOfItems);

    // new array to store all items
    var return_arr = [];

    // use async each, as per here http://justinklemm.com/node-js-async-tutorial/
    async.each(arr, function(item, callback) {

        // get items 1 by 1 and add to the return_arr
        SchemaNameHere.findById(item._id, function(err, data) {

            if (err) res.send(err);
            return_arr.push(data);

            // go to the next one item, or to the next function if done
            callback();

        });

    }, function(err) {

        // run this when looped through all items in arr
        res.json(return_arr);

    });

});