ceccode

db.avgexample.drop();

db.avgexample.insert({"name":"test1", "value": [1,2,3,4]});
db.avgexample.insert({"name":"test1", "value": [5,6,7,8]});

var map = function() {
        var sum = 0;
        var count = 0;
        for (var i = 0; i < this.value.length; i++) {

ceccode

var mongoose = require('mongoose'),

    // Load User model
    User = mongoose.model('User'),

    // Create Thing schema
    thingSchema = new mongoose.Schema({

      _user: {
        type: ObjectId,

ceccode

// Desired unique index: 
// db.collection.ensureIndex({ firstField: 1, secondField: 1 }, { unique: true})

db.collection.aggregate([
  { $group: { 
    _id: { firstField: "$firstField", secondField: "$secondField" }, 
    uniqueIds: { $addToSet: "$_id" },
    count: { $sum: 1 } 
  }}, 
  { $match: { 

ceccode

# mongodb.conf

# Note: if you run mongodb as a non-root user (recommended) you may
# need to create and set permissions for this directory manually,
# e.g., if the parent directory isn't mutable by the mongodb user.
dbpath=/usr/local/var/mongodb

#where to log
logpath=/usr/local/var/log/mongodb/mongo.log