Using UUIDs instead of ObjectIDs in MongoDB

Question

We are migrating a database from MySQL to MongoDB for performance reasons and considering what to use for IDs of the MongoDB documents. We are debating between using ObjectIDs,

Answer 1

Consider the amount of data you would store in each case.

A MongoDB ObjectID is 12 bytes in size, is packed for storage, and its parts are organized for performance (i.e. timestamp is stored first, which is a logical ordering criteria).

Conversely, a standard UUID is 36 bytes, contains dashes and is typically stored as a string. Further, even if you strip non-numeric characters and intend to store numerically, you must still content with its "indexy" portion (the part of a UUID v1 that is timestamp-based) is in the middle of the UUID, and doesn't lend itself well to sorting. There are studies done which allow for performant UUID storage, and I even wrote a Node.js library to assist in its management.

If you're intend on using a UUID, consider reorganizing it for optimal indexing and sorting; otherwise you'll likely hit a performance wall.