How is user_id generated with google-oauth2?

We have Auth0 configured to allow login with Google as a social connection. When people log in, they get a user_id in the form of google-oauth2|0011223344556677889900.

Where does this value come from, or how is it generated? Even when they log into a different Auth0 tenant, they still get the same user_id… or so I thought.

Until today, I’ve noticed that users with the same gmail address always have exactly the same user_id values among different Auth0 tenants. But today I came across a case where one user had different user_id values for the same email address! I think it’s probably related to the fact that the user’s email address changed after the initial account was created, and then one of the Auth0 accounts was deleted and re-created.

Where can I find documentation about this value that lays out exactly what assumptions are safe to make, and under what circumstances the value might change?

Hi @nic.waller,

The assumptions you can make are listed here:

There isn’t much in terms of guidance that we give. It looks like you can assume it will be unique, and you can predict the provider.

Hi @nancyhawkins181,

Im not sure I understand what you mean Can you explain?

That page didn’t quite answer my question, so I submitted a pull request to improve that page.

Thanks for adding the PR @nic.waller. The docs team will take a look.

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