Question

The Meteor Collection Object_Id does not appear to be the Mongo BSON Object_Id. This appears to be true based on conversation in IRC and https://github.com/meteor/meteor/blob/master/packages/uuid/uuid.js

Therefore, can it still be used to…

1. Use for ascending order?
2. Use for extracting insertion times?
3. Sort by ascending order, similar in nature to #1 and #2 though combined in scope of inquiry.

I believe this to be an important question for many that are considering building an application that requires optimization and is being designed according to Mongo docs. See http://www.mongodb.org/display/DOCS/Optimizing+Object+IDs for more info.

Answer 1

Heres the current implementation:

// RFC 4122 v4 UUID.
LocalCollection.uuid = function () {
  var s = [];
  var hexDigits = "0123456789abcdef";
  for (var i = 0; i < 36; i++) {
    s[i] = hexDigits.substr(Math.floor(LocalCollection.random() * 0x10), 1);
  }
  s[14] = "4";
  s[19] = hexDigits.substr((s[19] & 0x3) | 0x8, 1);
  s[8] = s[13] = s[18] = s[23] = "-";

  var uuid = s.join("");
  return uuid;
}

from: https://github.com/meteor/meteor/blob/bf46f04024251dea7a547c48d01d8032b7838d10/packages/minimongo/uuid.js

so the answer is, nope. It’s mostly random.