goosetest-609.js

var mongoose = require('mongoose');
mongoose.connect('localhost', 'test');

mongoose.set('debug', true)

var Foo = new mongoose.Schema({
    name: { type: String
          , index: { unique: true, background: true }
          }
}, { collection: 'a'});

var A = mongoose.model('a', Foo);

mongoose.connection.on('error', function (err) {
  // will show the index error
  console.log('connection err', err);
})

mongoose.connection.on('open', function () {
  console.log('running query...');

  A.find().run(function (err, docs) {
    console.log('\nquery error? %s', !! err, err && err.stack || '')

    // returns 101 docs instead of all in the collection
    console.log('returned %d docs', docs && docs.length || 0)

    mongoose.disconnect();
  })
});