Question

I have a mongo collection with documents. There is one field in every document which is 0 OR 1. I need to random sample 1000 records from the database and count the number of documents who have that field as 1. I need to do this sampling 1000 times. How do i do it ?

Answer 1

Here’s an example in the mongo shell .. assuming a collection of collname, and a value of interest in thefield:

var total = db.collname.count();
var count = 0;
var numSamples = 1000;

for (i = 0; i < numSamples; i++) {
    var random = Math.floor(Math.random()*total);
    var doc = db.collname.find().skip(random).limit(1).next();
    if (doc.thefield) {
        count += (doc.thefield == 1);
    }
}