. Can I create a random `client_id` for GA4 events if `user_id` is already included?

[Aiden]

Okay, here’s the interesting thing I’ve found. It turns out Google Analytics (GA) doesn’t play nice with a randomly generated client_id. If you try to send two events to GA’s Debug View, one with a legitimate client_id (think something along the lines of xxxxx.xxxxx) and another one with a bogus random client_id, only the one with the real deal pops up.

Looking again at GA4’s Measurement Protocol (MP) documentation, it appears client_id is a non-negotiable requirement while user_id is optional. This means you can’t skip sending a client_id. But, it seems unusual to me that GA isn’t cool with custom client_id. Looks like there’s still a bit more investigation needed on this topic!

[Ava]

The inclusion of both client_id and user_id in Google’s GA4 events might seem like an overlap, however, they serve different purposes. The client_id is used by Google Analytics to identify a unique browser or device, which is important for maintaining accuracy in session tracking. The user_id instead represents the unique ID of a user as recognized on your system, useful for identifying interactions of a specific user across multiple devices or sessions. Including a fake or random client_id could potentially interfere with this tracking and lead to inaccurate data, I wouldn’t recommend it. While the Google Analytics Help Center might not have specific resources on this, understanding how these IDs are used in tracking can help clarify their significance.