Uniqueness of AMIs, snapshotIDs and instance IDs

Our company provides some management on behalf of smaller businesses using Amazon EC2. Almost all our tasks are manual operations work, and therefore we are somewhat ignorant of the intricacies of EC2. However, I now want to build an ownership database, to show what attributes we manage for each customer. To build this database I will extract usage parameters from EC2. So I was wondering about the following mapping attributes: snapshot id, machine id and instan开发者_如何学编程ce id... Are these 3 attributes safe to be considered GLOBALLY UNIQUE? What about DATACENTER UNIQUE? Or do I need to add our client's account as a prefix in my database to ensure that mapping of attributes remains unique within our system?

Snapshot Id is regional, Instance Id is tied to an availability zone. There is no such thing as a machine id.