mongo.Guid-vs-ObjectId-performance

Comparing index performance on using Guids and ObjectIds with Mongo

I have always been told that non-sequential ids lead to drop in index performance, therefore I decided to test it. It's interesting to understand what percent of perfomance drop we are talking about. So I've chosen ObjectId as a highly sequential id and Guid as non-sequential one.

Update: According to my tests I can't notice any significant perfomance difference in reads, there is some on the write side, could you please advice what I am doing wrong? What test cases should I try to execute and compare?

Each test was performed at least 3 times.

Tip: There are several branches, each for each test-set (guid, objectId, etc).

	ObjectId	Guid	Sequential Guid	% perf drop1
1M inserts batched	13,401ms	37,138ms	39,291ms	177%
1M inserts	133,255ms	160,199ms	159,393ms	20%
10m inserts batched, with 10M documents already present	152,426ms	470,489ms	482,354ms	200%
10m inserts, with 10M documents already present	1,337,894ms	4,921,991ms		268%
Find document by id (24M docs)	25ms	25ms	22ms	0%
Skip 10M docs, take 1 (24M docs)	1,401ms	1,454ms	1,449ms	3.8%
Count docs where doc.id > randomId (24M docs)	48,363ms	not applicable (since operator ">") doesn't work for Guid
Index size for 24M docs	819MB	1225MB	50%

¹ percent of performance drop is calculated guid / objectid - 100 since objectId is a baseline

---

Raw results to be analysed later

ObjectId

docs inserted during past 60 seconds:0
docs inserted during past 60 seconds:3813220
docs inserted during past 60 seconds:3813220
docs inserted during past 60 seconds:4575864
docs inserted during past 60 seconds:3813220
docs inserted during past 60 seconds:4575864
docs inserted during past 60 seconds:3813220
docs inserted during past 60 seconds:3050576
docs inserted during past 60 seconds:4575864
docs inserted during past 60 seconds:3813220
docs inserted during past 60 seconds:4575864
docs inserted during past 60 seconds:3813220
docs inserted during past 60 seconds:3813220
docs inserted during past 60 seconds:3813220
docs inserted during past 60 seconds:3813220
docs inserted during past 60 seconds:3050576
docs inserted during past 60 seconds:3813220
docs inserted during past 60 seconds:3813220
docs inserted during past 60 seconds:4575864
docs inserted during past 60 seconds:3050576
docs inserted during past 60 seconds:3050576
docs inserted during past 60 seconds:3813220
docs inserted during past 60 seconds:3813220
docs inserted during past 60 seconds:3813220
docs inserted during past 60 seconds:1525288
docs inserted during past 60 seconds:3050576
docs inserted during past 60 seconds:3813220
docs inserted during past 60 seconds:3050576
100000000 BATCH documents insertion with time: 1628639ms
0.01628639ms per document
docs inserted during past 60 seconds:93636
5139193d932bdc5e346ff3a7
Skip 10 000 000 docs and take one time: 11075ms
Reading one document by id time: 421ms //not so true, other test proved that avg is ~42ms