Shows one case where parallel connections to MongoDB give a substantial speedup

node mongodb write-then-read

// Modified from node-mongodb-native example
sys = require("sys");

var Db = require('mongodb').Db,
  Connection = require('mongodb').Connection,
  Server = require('mongodb').Server,
  // BSON = require('mongodb').BSONPure;
  BSON = require('mongodb').BSONNative;

var host = process.env['MONGO_NODE_DRIVER_HOST'] != null ? process.env['MONGO_NODE_DRIVER_HOST'] : 'localhost';
var port = process.env['MONGO_NODE_DRIVER_PORT'] != null ? process.env['MONGO_NODE_DRIVER_PORT'] : Connection.DEFAULT_PORT;

sys.puts("Connecting to " + host + ":" + port);
var db1 = new Db('node-mongo-examples', new Server(host, port, {}), {native_parser:true});
var db2 = new Db('node-mongo-examples', new Server(host, port, {}), {native_parser:true});


function aString(length) {
  var str = '';
  for (var i = 0; i < length; i++) {
    str += 'a';
  }
  return str;
}
var x = aString(1 * 1000 * 1000);

var dt = new Date();
var logTime = function(rg) {
  rg.push((new Date).getTime() - dt.getTime());
  sys.puts(rg);
};

logTime(["start"]);
var nFound = 0;
db1.open(function(err, db1) {
  db2.open(function(err, db2) {
    db1.collection('test', function(err, collection) {
      logTime(["connected"]);
      collection.remove(function(err, collection) {
        logTime(["removed"]);
        var fx = function(db, n) {
          db.collection('test', function(err, collection) {

            // Insert 3 records
            for(var i = 0; i < 3; i++) {
              collection.insert({'a':x}, function(err) {
                logTime(["inserted", n]);
              });
            }

            logTime(["about to find"]);
            collection.find(function(err, cursor) {
              cursor.each(function(err, item) {
                logTime(["found", item, n, ++nFound]);
              });
            });
          });
        };
        fx(db1, 1);

        // Switch which of the following two lines is commented out to test the 1db vs. 2 db case
        fx(db2, 2);
        //fx(db1, 1);

      });
    });
  });
});