Use Buffer equals when comparing ObjectId #287

siboulet · 2018-11-06T04:48:49Z

This PR updates ObjectId #equals to use internal Node.js buffer #equals function when comparing two ObjectId objects.

While tracing performance issue in our MongoDB based app, I found #equals was calling toString() when comparing two ObjectId, which turns out to be quite inefficient. In our own testing this change appears to be much, much faster when comparing two ObjectIds.

Update ObjectId #equals to use internal Node.js buffer #equals function when comparing two ObjectId objects.

Compare last random bytes from ObjectId prior to doing a full ObjectId comparison.

siboulet · 2018-11-06T05:17:20Z

I'm not sure how far we want to go with this in term of optimization, but I've just pushed an updated version that checks the last random bytes from ObjectId before doing a full equality check. In my testing, the first version was about ~200% faster (doing thousands of comparisons), and the refined version that adds the 12th byte check is another ~200% faster.

daprahamian · 2018-11-12T16:11:28Z

@siboulet how much of a performance impact are you seeing? Is the toString call taking up a significant part of your execution?

siboulet · 2018-11-12T16:28:48Z

@daprahamian i'm seeing a huge impact ! 200%+ slowdown when dealing with thousands of documents. toString() was the culpit. Why toString() when we can use Buffer equals?

daprahamian · 2018-11-12T16:48:14Z

@siboulet I'm mostly asking about the performance impact in ms. It may take twice as long, but a 2x increase on a negligible number can still be negligible.

The main hesitation on our part is that we need bson to run in the browser, where Buffer is a polyfill. Do you have performance numbers for this change in the browser version of bson?

siboulet · 2018-11-12T17:03:26Z

@daprahamian OK let me try to come up with some benchmark. My use case is on Node.js side doing filtering of a large array of ObjectId.

mbroadst · 2018-11-12T19:03:39Z

@siboulet could you also give us a little more details about your actual use case here? Specifically, how do you find yourself comparing object id's this often? Perhaps a small code same could illuminate the case for us all!

kYem · 2020-05-10T17:44:53Z

Any update on this one?

The performance difference is huge, and I though it was quite common to filter, find something by id.

Sample test

const ObjectId = require("bson").ObjectId;

const data = [];
const id = "5c9031000000000000000000";
const lastId = new ObjectId(id);

const runs = 1000000;
for (let i = 1; i < runs; i++) {
  data.push(new ObjectId());
}
data.push(lastId);
const results = [];

function runFilter(name, cb) {
  const now = Date.now();
  let length = data.filter(cb).length;
  results.push({ name, length, time: Date.now() - now });
}

console.log(`Running tests on ${data.length} ids array`);
runFilter("Filter toString to string", s => s.toString() === id);
runFilter("Filter toStringBoth", s => s.toString() === lastId.toString());
runFilter("Filter String() Both", s => String(s) === String(lastId));
runFilter("Filter equals objectId", s => s.equals(lastId));
runFilter("Filter equals to string", s => s.equals(id));
runFilter("Filter direct id", s => s.id === lastId.id);
runFilter(
  "Filter buffer equals",
  s => s.id[11] === lastId.id[11] && s.id.equals(lastId.id)
);
console.log(JSON.stringify(results, null, 2));

Results:

[
  {
    "name": "Filter toString to string",
    "length": 1,
    "time": 1905
  },
  {
    "name": "Filter toStringBoth",
    "length": 1,
    "time": 2903
  },
  {
    "name": "Filter String() Both",
    "length": 1,
    "time": 3126
  },
  {
    "name": "Filter equals objectId",
    "length": 1,
    "time": 3030
  },
  {
    "name": "Filter equals to string",
    "length": 1,
    "time": 2103
  },
  {
    "name": "Filter direct id",
    "length": 1,
    "time": 20
  },
  {
    "name": "Filter buffer equals",
    "length": 1,
    "time": 26
  }
]

Sandbox example: https://codesandbox.io/s/mystifying-cookies-7tlv3?file=/src/index.js

We are talking about ~20x-100x on suggested current equals implementation.
In nodejs its closer to 10x-20x improvements.

It has been a real performance issue where _id conversion to string was taking significant % of the execution time, to the point that we were trying to use other properties for filter/find functionality in nodejs.

pooooodles · 2021-04-08T15:20:58Z

https://jira.mongodb.org/browse/NODE-3015

Uzlopak · 2021-12-29T12:30:03Z

What happens if you compare byte by byte instead of using equals? Would it slow down? If it is working properly it could be merged as it is not only working in node

Uzlopak · 2022-01-19T23:52:17Z

const ObjectId = require("./lib/objectid").ObjectId;

const data = [];
const id = new ObjectId().toString();
const lastId = new ObjectId();

const runs = 10000000;
for (let i = 1; i < runs; i++) {
data.push(newObjectId());
}
data.push(lastId);
const results = [];

function runFilter(name, cb) {
constnow = Date.now();
letlength = data.filter(cb).length;
results.push(\{ name, length, time:Date.now() - now });
}

console.log(`Running tests on ${data.length} ids array`);
runFilter("Filter toString to string", s => s.toString() === id);
runFilter("Filter toStringBoth", s => s.toString() === lastId.toString());
runFilter("Filter String() Both", s => String(s) === String(lastId));
runFilter("Filter equals objectId", s => s.equals(lastId));
runFilter("Filter equals to string", s => s.equals(id));
runFilter("Filter direct id", s => s.id === lastId.id);
runFilter(
"Filter buffer equals",
s=>Buffer.compare(s.id, lastId.id) === 0
);
runFilter(
"Check all bytes in order",
s=> (
// first two timestamp bytes
s.id[0] === lastId.id[0] &&
s.id[1] === lastId.id[1] &&
// last two timestamp bytes
s.id[2] === lastId.id[2] &&
s.id[3] === lastId.id[3] &&
// three bytes machine id
s.id[4] === lastId.id[4] &&
s.id[5] === lastId.id[5] &&
s.id[6] === lastId.id[6] &&
// two bytes process id
s.id[7] === lastId.id[7] &&
s.id[8] === lastId.id[8] &&
// last three incrementor bytes
s.id[9] === lastId.id[9] &&
s.id[10] === lastId.id[10] &&
s.id[11] === lastId.id[11]
)
);
runFilter(
"Check all bytes reverse",
s=> (
// last three incrementor bytes
s.id[11] === lastId.id[11] &&
s.id[10] === lastId.id[10] &&
s.id[9] === lastId.id[9] &&
// two bytes process id
s.id[8] === lastId.id[8] &&
s.id[7] === lastId.id[7] &&
// three bytes machine id
s.id[6] === lastId.id[6] &&
s.id[5] === lastId.id[5] &&
s.id[4] === lastId.id[4] &&

// last two timestamp bytes
s.id[3] === lastId.id[3] &&
s.id[2] === lastId.id[2] &&
// first two timestamp bytes
s.id[1] === lastId.id[1] &&
s.id[0] === lastId.id[0]
)
);
runFilter(
"Check all bytes in significance order",
// last three incrementor bytes
s=> (
s.id[11] === lastId.id[11] &&
s.id[10] === lastId.id[10] &&
s.id[9] === lastId.id[9] &&

// last two timestamp bytes
s.id[3] === lastId.id[3] &&
s.id[2] === lastId.id[2] &&
s.id[1] === lastId.id[1] &&
s.id[0] === lastId.id[0] &&
// two bytes process id
s.id[8] === lastId.id[8] &&
s.id[7] === lastId.id[7] &&
// three bytes machine id
s.id[6] === lastId.id[6] &&
s.id[5] === lastId.id[5] &&
s.id[4] === lastId.id[4]
// first two timestamp bytes
)
);
runFilter(
"Check the most significant bytes first",
s=> (
// last two timestamp bytes
s.id[3] === lastId.id[3] &&
// s.id[2] === lastId.id[2] &&
 
// last three incrementor bytes
s.id[11] === lastId.id[11] &&
s.id[10] === lastId.id[10] &&
s.id[9] === lastId.id[9] &&
 
Buffer.compare(s.id, lastId.id) === 0
)
);
runFilter(
"Filter buffer using equals",
s=>s.id[11] === lastId.id[11] && s.id.equals(lastId.id)
);
runFilter(
"Filter buffer using compare",
s=>s.id[11] === lastId.id[11] && Buffer.compare(s.id, lastId.id) === 0
);
console.log(JSON.stringify(results, null, 2));

And the result:

Running tests on 10000000 ids array
[
  {
    "name": "Filter toString to string",
    "length": 0,
    "time": 1650
  },
  {
    "name": "Filter toStringBoth",
    "length": 1,
    "time": 3018
  },
  {
    "name": "Filter String() Both",
    "length": 1,
    "time": 4747
  },
  {
    "name": "Filter equals objectId",
    "length": 1,
    "time": 2997
  },
  {
    "name": "Filter equals to string",
    "length": 0,
    "time": 9798
  },
  {
    "name": "Filter direct id",
    "length": 1,
    "time": 104
  },
  {
    "name": "Filter buffer equals",
    "length": 1,
    "time": 972
  },
  {
    "name": "Check all bytes in order",
    "length": 1,
    "time": 188
  },
  {
    "name": "Check all bytes reverse",
    "length": 1,
    "time": 175
  },
  {
    "name": "Check all bytes in significance order",
    "length": 1,
    "time": 177
  },
  {
    "name": "Check the most significant bytes first",
    "length": 1,
    "time": 177
  },
  {
    "name": "Filter buffer using equals",
    "length": 1,
    "time": 172
  },
  {
    "name": "Filter buffer using compare",
    "length": 1,
    "time": 173
  }
]

Uzlopak · 2022-01-20T00:05:46Z

Created a followup PR #478

dariakp · 2022-01-20T15:18:29Z

Closing this in favor of #478 that does not have merge conflicts

siboulet added 2 commits November 5, 2018 23:46

Use Buffer equals when comparing ObjectId

58cc055

Update ObjectId #equals to use internal Node.js buffer #equals function when comparing two ObjectId objects.

More ObjectId equals optimization

61bd669

Compare last random bytes from ObjectId prior to doing a full ObjectId comparison.

pooooodles added the tracked-in-jira There is a ticket in Mongo's Jira instance tracking this issue/PR label Apr 8, 2021

Uzlopak mentioned this pull request Jan 20, 2022

fix(NODE-3015): ObjectId.equals should use Buffer.equals for better performance #478

Merged

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dariakp closed this Jan 20, 2022

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Use Buffer equals when comparing ObjectId #287

Use Buffer equals when comparing ObjectId #287

siboulet commented Nov 6, 2018 •

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siboulet commented Nov 6, 2018 •

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daprahamian commented Nov 12, 2018 •

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siboulet commented Nov 12, 2018

daprahamian commented Nov 12, 2018

siboulet commented Nov 12, 2018

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pooooodles commented Apr 8, 2021

Uzlopak commented Dec 29, 2021

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dariakp commented Jan 20, 2022

Use Buffer equals when comparing ObjectId #287

Use Buffer equals when comparing ObjectId #287

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siboulet commented Nov 6, 2018 • edited Loading

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