stackoverflow-sort3.js

// sort3 uses nedb, as suggested by Tamas Hegedus
//////////////////////////////////////////////////////////////////////////////////////
var fs = require('fs'),
    readline = require('readline');

var Datastore = require('nedb');
var db = new Datastore({
    filename: 'path/to/temp/datafile',
    autoload: true
});

var rl = readline.createInterface({
    input: fs.createReadStream('./input.txt'),
    terminal: false
});
var writer = fs.createWriteStream('out3.txt');

rl.on('line', function (line) {
    var tmp = line.split("\t").reverse();
    db.insert({
        field0: tmp[0],
        field1: tmp[1],
        field2: tmp[2]
    });
});

rl.on('close', function () {
    var cursor = db.find({})
        .sort({field0: 1}); // sort by field0, ascending
    var PAGE_SIZE = 1000;
    paginate(0);
    function paginate(i) {
        cursor.skip(i * PAGE_SIZE).limit(PAGE_SIZE).exec(function (err, docs) {
            // handle errors

            docs.forEach(o => writer.write(o.field0 + "\t" + o.field1 + "\t" + o.field2 + "\n"));

            if (docs.length >= PAGE_SIZE) {
                paginate(i + PAGE_SIZE);
            } else {
                // cleanup temp database

                writer.end();
                var closetime = Date.now();
                console.log('Time. ', (closetime - start) / 1000, ' secs');
            }
        });
    }
});