This post takes a deep dive into the databases that support SharePoint’s User Profile Application (UPA). The databases that support UPA are the Social DB, Sync DB, and Profile DB. We will focusing on the Profile DB, the large tables that exist in this database and what they are for. If you are looking to minimize the size of the Profile DB, this article will give tips on how to do that.
We also take a look at what the estimated size of the profile DB would be if you went past the supported limit of 2 million profiles (http://technet.microsoft.com/en-us/library/cc262787(v=office.14).aspx). We take a look at a hypothetical UPA with 4 million profiles in it. Three scenarios were evaluated: 10,000 active users, 100,000 active users, and 1,000,000 active users. An active user is defined as someone who has actually gone to their profile through the My Site host and edited at least one aspect of their profile.
See attached Word document (UPA Info For Blog.docx).