Firebase Analytics: first_open event missing for part of my users

0
votes

I'm creating some funnels and journeys for my app's events from Firebase Analytics using BigQuery, starting with first_open and continuing with other custom events. My understanding is that using user_pseudo_id, I should be able to track a single user's journey.

The problem I'm facing is that some user_pseudo_ids found in the custom events do not have a corresponding first_open event, so I'm not sure when they started using my app.

Are there cases where a first_open may not be recorded? Or cases where the user_pseudo_id may change after first_open?

1
firebasefirebase-analytics

1 Answers

1
votes

TL;DR: In order to reliably track users, one should use setUserId().

As noted in this answer, user_pseudo_id comes from getAppInstanceId(), and it's reasonable to assume its lifetime is not dissimilar to FirebaseInstanceId, which can change in the following cases:

  • App deletes Instance ID
  • App is restored on a new device
  • User uninstalls/reinstall the app
  • User clears app data

Reinstalling triggers the first_open event again, so that wouldn't be my case, and my app does not delete the Instance ID.

Going through the logs, the last option can be discarded (in my case), because I can see the users were logged into my app when the new user_pseudo_id started being used.

So that leaves restoring the app on a new device as the likely culprit.

I'm now using setUserId() in order to track users.