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
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