u/NecessaryTicket5373

I’m a beginner building a web service by myself. Our internal user_id is already a random UUID.

For GA4 User-ID, which approach is commonly used in real production services?

1. Use the internal user_id directly
2. HMAC/hash the internal user_id
3. Create a separate random ga4_id only for GA4

There are no existing users yet, so adding a ga4_id column would be easy.

I’m mainly curious about what people actually use in production and why.