The funny thing is that if you ask Claude if you should use email address as a primary key it will pretty adamantly warn you away from it:

> I'd recommend against using email as the primary key for a large LLM chat website. Here's why:

> Problems with email as primary key:

> 1. Emails change - Users often want to update their email addresses. With email as PK, you'd need to cascade updates across all related tables (chat sessions, messages, settings, etc.), which is expensive and error-prone

> [Edited for length]