top_mongo_collections

function getReadableFileSizeString(fileSizeInBytes) {
    var i = -1;
    var byteUnits = [' kB', ' MB', ' GB', ' TB', 'PB', 'EB', 'ZB', 'YB'];
    do {
        fileSizeInBytes = fileSizeInBytes / 1024;
        i++;
    } while (fileSizeInBytes > 1024);

    return Math.max(fileSizeInBytes, 0.1).toFixed(1) + byteUnits[i];
};

var collectionNames = db.getCollectionNames(), stats = [];
collectionNames.forEach(function (n) { stats.push(db.getCollection(n).stats()); });

function sortCollectionsBy(key) {
	print("Sorting by " + key);
	print("==================")
	stats = stats.sort(function(a, b) { return b[key] - a[key]; });
	for (var c in stats) { print(stats[c]['ns'] + ": " + getReadableFileSizeString(stats[c][key])); }
}

sortCollectionsBy('size');
sortCollectionsBy('storageSize');
sortCollectionsBy('totalIndexSize');
sortCollectionsBy('count');