How do I load a random document from CouchDB (efficiently and fairly)?

Question

I would like to load a random document out of a set of documents stored in a CouchDB database. The method for picking and loading the document should conform to the following re

Answer 1

I agree with @meliodas:

Here's the distribution of option 2 (n=1000):

{ 0.2: 233,
  0.9: 767 }

And with swapping startkey/endkey half the time:

{ 0.2: 572,
  0.9: 428 }

Not sure what happens to the distribution when you look at more data, but it initially seems a bit more promising. This is without using option 1 at all, which I don't think is necessary.