fan out on write with bucketing

gistfile1.js

//Fan out on Write
//H Shard on “owner I sequence"
db.shardCollection("myapp.inbox". { "owner": 1, "sequence":1 });
db.shardCollection("myapp.users", { "user name":1 });
msg = {
  from: "Joe",
  to: [ "Bob". "Jane" ],
  sent: new Date().
  message: "Hi!",
}
// Send a message
for( recipient in msg.to) {
  sequence = db.users.findAndModity({
  query:  {'user_name': recipient},
  update: { '$inc': { 'msg_count': 1 }},
  upsert: true,
  new: true }).msg_count / 50;

db.inbox.update({owner: recipient, sequence: sequence}.
                {$push: { 'messages': msg } },
                {upsert: true });
}
// Read my inbox
db.inbox.find({ owner: "Joe" }).sort({ sequence: -1 }).limit(2)