🐛 [firebase_analytics] first_open event is being fired many times by same app instance

[alectogeek]

Bug report

I'm comparing data from different analytics services and see that first_open in firebase_analytics is duplicated (or even worse).
For example, in Android:

First_open: 1 Nov (comparison with appsFlyer):
AppsFlyer 267
Firebase 475

First_open: 1 Nov (comparison with google ads considering compaign)
Google Ads report: 122
Firebase (Audience: adsCompaign): 231 

So the difference is up to 47 percent!

Then I went to BigQuery and tried to understand what is going on.

My query was:

SELECT user_pseudo_id FROM `analytics_210753586.*`, UNNEST(user_properties) AS user_properties, UNNEST(event_params) AS event_params  
WHERE 
  event_name = 'first_open' AND
  user_properties.key = "first_open_time" 
  AND CAST(user_properties.value.int_value AS int64) BETWEEN 1604098800000 AND 1604185200000
  AND device.operating_system = 'ANDROID'

and I could see that the first_open event is duplicated 7 times each! For iOS the duplication is 6 times for each. But here I'm not sure if my query is correct.

My custom events sending using FirebaseAnalytics().logEvent() seems to be ok.

Firebase analytics package version is firebase_analytics 6.0.1 for android and 6.1.0 for iOS.

Flutter doctor

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Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel unknown, 1.20.4, on Mac OS X 10.15.7 19H2, locale en-RU)
 
[✓] Android toolchain - develop for Android devices (Android SDK version 29.0.2)
[✓] Xcode - develop for iOS and macOS (Xcode 12.1)
[✓] Android Studio (version 4.0)
[✓] VS Code (version 1.50.1)
[✓] Connected device (1 available)

• No issues found!

[markusaksli-nc]

Strange, I get 1 event for every device when testing with the latest flutter master 1.24.0-8.0.pre.113 and firebase_analytics: ^6.1.0 using the official example.

flutter doctor -v

[√] Flutter (Channel master, 1.24.0-8.0.pre.113, on Microsoft Windows [Version 10.0.19041.572], locale et-EE)
    • Flutter version 1.24.0-8.0.pre.113 at C:\Development\flutter_master
    • Framework revision a75b5b6c8f (4 hours ago), 2020-11-06 01:19:02 -0500
    • Engine revision 0693ee04d1
    • Dart version 2.12.0 (build 2.12.0-21.0.dev)

[√] Android toolchain - develop for Android devices (Android SDK version 30.0.2)
    • Android SDK at C:\Users\marku\AppData\Local\Android\sdk
    • Platform android-30, build-tools 30.0.2
    • Java binary at: C:\Users\marku\AppData\Local\JetBrains\Toolbox\apps\AndroidStudio\ch-0\201.6858069\jre\bin\java
    • Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b01)
    • All Android licenses accepted.

[√] Chrome - develop for the web
    • Chrome at C:\Program Files\Google\Chrome\Application\chrome.exe

[√] Visual Studio - develop for Windows (Visual Studio Community 2019 16.7.7)
    • Visual Studio at C:\Program Files (x86)\Microsoft Visual Studio\2019\Community
    • Visual Studio Community 2019 version 16.7.30621.155
    • Windows 10 SDK version 10.0.18362.0

[√] Android Studio (version 4.1.0)
    • Android Studio at C:\Users\marku\AppData\Local\JetBrains\Toolbox\apps\AndroidStudio\ch-0\201.6858069
    • Flutter plugin can be installed from:
       https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
       https://plugins.jetbrains.com/plugin/6351-dart
    • Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b01)

[√] IntelliJ IDEA Ultimate Edition (version 2020.2)
    • IntelliJ at C:\Users\marku\AppData\Local\JetBrains\Toolbox\apps\IDEA-U\ch-0\202.7660.26
    • Flutter plugin can be installed from:
       https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
       https://plugins.jetbrains.com/plugin/6351-dart

[√] Connected device (6 available)
    • SM G950F (mobile)           • ce12171c51cc001c03 • android-arm64  • Android 9 (API 28)
    • sdk gphone x86 arm (mobile) • emulator-5554      • android-x86    • Android 11 (API 30) (emulator)
    • Windows (desktop)           • windows            • windows-x64    • Microsoft Windows [Version 10.0.19041.572]
    • Web Server (web)            • web-server         • web-javascript • Flutter Tools
    • Chrome (web)                • chrome             • web-javascript • Google Chrome 86.0.4240.183
    • Edge (web)                  • edge               • web-javascript • Microsoft Edge 86.0.622.61

• No issues found!

Are you sure the baseline for AppsFlyer is correct? Is the event exactly the same?

[alectogeek]

In AppsFlyer I use my custom event which I report in my main function. I added the same custom event for firebase, so looking forward to further results. Will notify you about my observes.

[alectogeek]

So, I did an additional investigation and I found some interesting facts.
I compared data from the firebase dashboard, BigQuery, and AppsFlyer.

First I compared the range from 3 to 9 November for the android platform:

firebase - 1442
BQ - 863
appsFlyer - 847
GP console - 668

Then I tried to compare a bit larger range using one additional event. Here is data from 3 sources with some screenshots:

From Oktober 20 to Oktober 30 from BigQuery:

first_open - 3156
user_swiped_1_section - 3139

From Oktober 20 to Oktober 30 from Firebase dashboard:

first_open - 5530
user_swiped_1_section - 3158

GP installs 20 - 30 Oktober:
3307

How is that possible that the firebase dashboard show way more first_open events even in comparison with BigQuery?