200万件のCSVをparseしつつMongoDBに素早く突っ込むにはBulk()を使う（Nodeでやってみた） ref: http://qiita.com/varmil/items/be53a562393dcfb8867e

bad.js

var fs = require('fs');
var MongoClient = require('mongodb').MongoClient;
var CSV = require('comma-separated-values');

var NAME_MONGO_DB = 'eijiro';
var NAME_MONGO_COLLECTION = 'words';
var url = 'mongodb://localhost:27017/' + NAME_MONGO_DB;

var inputCsv = process.argv[2];
var text = fs.readFileSync(inputCsv, 'utf-8');

// data: example [ {a : 1}, {a : 2}, {a : 3} ]
var insertDocuments = function(db, data, callback) {
    // Get the documents collection
    var collection = db.collection(NAME_MONGO_COLLECTION);
    // Insert some documents
    collection.insert(data, function(err, result) {
        if (err) return console.error(err);
        callback(result);
    });
};

MongoClient.connect(url, function(err, db) {
    if (err) return console.error(err);

    var rows = new CSV(text, { header: true, cast: false }).parse();

    insertDocuments(db, rows, function(result) {
        db.close();
    });
});

file0.txt

# コマンド例
node good.js eijiro_dic_utf8.csv

good.js

var fs = require('fs');
var MongoClient = require('mongodb').MongoClient;
var CSV = require('comma-separated-values');

var NAME_MONGO_DB = 'eijiro';
var NAME_MONGO_COLLECTION = 'words';
var url = 'mongodb://localhost:27017/' + NAME_MONGO_DB;

var inputCsv = process.argv[2];
var text = fs.readFileSync(inputCsv, 'utf-8');

MongoClient.connect(url, function(err, db) {
    if (err) return console.error(err);

    var col = db.collection(NAME_MONGO_COLLECTION);
    var batch = col.initializeUnorderedBulkOp();

    new CSV(text, { header: true, cast: false }).forEach(function(obj) {
        batch.insert(obj);
    });

    batch.execute(function(err, result) {
        db.close();
        if (err) console.err(err);
        process.exit();
    });
});