Updating and saving thousands of objects at once on Parse Server using cloud code. Code doesn't work for more than 2 objects. (Parse.Object.saveAll())

Question

In my parse server I have a class called Stats which contains the columns secondsPlayed (number) and timeScore (number)

I am using cloud code to update all the rows in the column timeScore

The code below works only when updating and saving 1 or 2 objects results.length. If Parse.Query returns more than 2 results the code crashes and I get the following error.

error: Failed running cloud function timeScore for user undefined with:
Input: {}
Error: {"code":101,"message":"Object not found."} functionName=timeScore, code=101, message=Object not found., , user=undefined
error: Error generating response. ParseError { code: 101, message: 'Object not found.' } code=101, message=Object not found.
error: Object not found. code=101, message=Object not found.

This is a problem as I need to update and save thousands of objects. What is the best and fastest way to do this?

Why does my code work for 2 objects but not for more than 2? How can I fix this?

Here is my code

    var _ = require("underscore");

Parse.Cloud.define("timeScore", function(request, response) {

    var query = new Parse.Query("Stats");
    query.greaterThan("secondsPlayed", 1000);
    query.find().then(function(results) {

        _.each(results, function(result) {
            var secondsPlayed = result.get("secondsPlayed") || 0;
            result.set("timeScore", secondsPlayed*2);

        });
        return Parse.Object.saveAll(results);

    }).then(function(results) {

        response.success(results);
    }, function(error) {

        response.error(error);
    }); });

Here is how I call it

#!/usr/bin/env node
var Parse = require("parse/node");
Parse.initialize("xx",   "xx");
Parse.serverURL = "http://randomapp.herokuapp.com/parse";
Parse.Cloud.run('timeScore');

UPDATE:

Below is my latest code. Everything works well except for the fact that I get the following error for no apparent reason.

heroku[router]: at=error code=H12 desc="Request timeout" method=POST path="/parse/functions/timeScore

I get the timeout error regardless of what batchSize I choose and I get it every 30 seconds. I get it a total of 5 times. After the 5th time I dont get it anymore. I get the 5th and last error at around 2.5 minutes into the process (30seconds*5). This error does not effect the process in any way. All 250k objects are updated and saved regardless of batchSize.

I thought maybe because I never call results.error or results.success the server thinks I am still doing some work and shows the error. However I updated my code as the following and I still get the timeout errors.

Also after each timeout error processBatch() is called once again from the beggining. Since I get 5 timeout errors processBatch() gets called 5 times. So after the 5th timeout error there is 5 processBatch() functions running simultaneously (I confirmed this with logs).

What is causing the heroku timeout errors I am getting? How do I fix it?

var _ = require("underscore");
Parse.Cloud.define("timeScore", function(request, response) {
var counter = 0;
function processBatch(query, batchSize, startingAt, process) {
    query.limit(batchSize);
    query.skip(startingAt);

    return query.find().then(results => {

        return process(results).then(() => results.length);
    }).then(length => {

        return (length === batchSize)? processBatch(query, batchSize, startingAt+length, process) : {};
    });
}

function setTimeScores(stats) {
        console.log("LENGTH " + stats.length);
    _.each(stats, stat => {

        counter ++;
        stat.set("timeScore", counter);

    });
    return Parse.Object.saveAll(stats);
}

var query = new Parse.Query("Stats");

processBatch(query, 2500, 0, setTimeScores).then(results => {
        response.success(results);
    }).catch(error => {
        response.error(error);
    });

});

Answer 1

To handle numbers of objects greater than the max query limit, build a more abstract function that uses query's limit() and skip() to cursor through the data:

function processBatch(query, batchSize, startingAt, process) {
    query.limit(batchSize);
    query.skip(startingAt);
    return query.find().then(results => {
        return process(results).then(() => results.length);
    }).then(length => {
        return (length === batchSize)? processBatch(query, batchSize, startingAt+length, process) : {};
    });
}

This says, get one, batchSize-long batch of objects specified by query, then do something with the retrieved objects, then, if there might be more, do the same thing again, skipping objects we've processed already.

Your process step looks like this:

function setTimeScores(stats) {
    _.each(stats, stat => {
        var secondsPlayed = stat.get("secondsPlayed") || 0;
        stat.set("timeScore", secondsPlayed*2);
    });
    return Parse.Object.saveAll(stats);
}

Call it like this:

let query = new Parse.Query("Stats");
query.greaterThan("secondsPlayed", 1000);
processBatch(query, 100, 0, setTimeScores);

EDIT in the context of a cloud function, call it like this...

Parse.Cloud.define("computeStats", function(request, response) {
    let query = new Parse.Query("Stats");
    query.greaterThan("secondsPlayed", 1000);
    processBatch(query, 100, 0, setTimeScores).then(results => {
        response.success(results);
    }).catch(error => {
        response.error(error);
    });
});