EWS Appointment ID. Unique?

Question

Is the Appointment.Id property or Appointment.Id.UniqueId really unique?

I have the simplest of methods, retrieving Appointments using ExchangeService.FindAppointments. My results are showing a few appointments with a different subject but the same Appointment.Id.UniqueId!

Am I missing something?

Answer 1

They are definitely unique. However, they are generated to be sequential, or close to sequential, so appointments created close together are likely to have very similar unique IDs. It's also worth noting that they are case sensitive. Are you sure that you're making a case-sensitive comparison? See the comment next to the ID property at http://msdn.microsoft.com/en-us/library/aa580234.aspx.

Answer 2

As agt says, they are Unique, but they are subject to change.

If an Appointment (or anything inherited from Item) is moved to another folder/mailbox, the UniqueId will change, and the ChangeKey will as well.

Answer 3

disregard the first verison of my comment completely. For everyone who is as stupid as me: They really are case sensitive. They can be identical except for their case. Don't trust Powershell (it doesn't do case sensitive comparisment per default), don't trust your editor (it most likely doesn't do case sensitive search per default either), and don't trust your mysql database if you have the collation set to anything that ends with _ci.