makeId = function (doc) {
    var id = Math.floor(Math.random() * 900000) + 100000, that = this; // max(900000)/min(100000)
    var key = "", i, v, that = this;

    for (i = 0; i < 32; i++) {
        v = Math.random() * 16 | 0;

        if (i == 8 || i == 12 || i == 16 || i == 20) {
            key += '-';
        }

        if (i == 12) {
            key += '4';
        } else {
            key += (i == 16 ? (v & 3 | 8) : v).toString(16);
        }
    }

    var res = db.users.findOne({$or: [
        {id: id},
        {key: key}
    ]});    
    
    if(res) {
        makeId(doc);
    } else {
        doc.id = id; 
        doc.key = key; 
        db.users.save(doc);

        print(id); 
    }   
}
    
db.users.ensureIndex({id:1},{unique:true,sparse:true})
db.users.ensureIndex({key:1},{unique:true,sparse:true})

db.users.find().limit(10).forEach(function(doc){ makeId(doc); })



db.friends.find().limit(100000).forEach(function (doc) {
    var user = db.users.findOne({mysql_id: doc.user2});
    var friend = db.users.findOne({mysql_id: doc.user1});

    if (user && friend) {
        if (!(db.users.findOne({mysql_id: doc.user2, followers: friend._id}))) {
            user.followers.push(friend._id);
            db.users.save(user);

            print(friend._id);
        }
    }
});

makeId = function (doc) {
    var id = Math.floor(Math.random() * 900000) + 100000, that = this; // max(900000)/min(100000)
    var key = "", i, v, that = this;

    for (i = 0; i < 32; i++) {
        v = Math.random() * 16 | 0;

        if (i == 8 || i == 12 || i == 16 || i == 20) {
            key += '-';
        }

        if (i == 12) {
            key += '4';
        } else {
            key += (i == 16 ? (v & 3 | 8) : v).toString(16);
        }
    }

    var res = db.users.findOne({$or: [
        {id: id},
        {key: key}
    ]});    
    
    if(res) {
        makeId(doc);
    } else {
        doc.id = id; 
        doc.key = key; 
        db.users.save(doc);

        print(id); 
    }   
}
    
db.users.ensureIndex({id:1},{unique:true,sparse:true})
db.users.ensureIndex({key:1},{unique:true,sparse:true})

db.users.find().limit(10).forEach(function(doc){ makeId(doc); })

MongoDB

MongoDB Shell Commands

JavaScript