Random record from MongoDB

Question

I am looking to get a random record from a huge (100 million record) mongodb.

What is the fastest and most efficient way to do so? The data is already t

Answer 1

What works efficiently and reliably is this:

Add a field called "random" to each document and assign a random value to it, add an index for the random field and proceed as follows:

Let's assume we have a collection of web links called "links" and we want a random link from it:

link = db.links.find().sort({random: 1}).limit(1)[0]

To ensure the same link won't pop up a second time, update its random field with a new random number:

db.links.update({random: Math.random()}, link)