Why is the size of my SharePoint 2010 User Profile Service sync database so large? Can I shrink it?

Why is the size of my SharePoint 2010 User Profile Service sync database so large? Can I shrink it? 

 

There's a blog post about this here; http://blogs.technet.com/b/praveenh/archive/2011/12/14/user-profile-synchronization-database-growing-out-of-control.aspx 

 

There are new stored procedures in the Feb 2012 cumulative update that will keep the size under control.  If you have that patch installed you can run the following:

$timerJob = (Get-SPTimerJob | ? { $_.TypeName -eq "Microsoft.Office.Server.UserProfiles.UserProfileImportJob" })
 $timerJob.KeepHistoryInterval = 1
 $timerJob.Update()
 $timerJob | Start-SPTimerJob


Adjust the KeepHistoryInterval to your liking.  It tells the Sync database how many days of sync history to keep (which is what makes the database grow and grow).