This is a “Window” into the vRA's internal database. I had a hard time finding good documentation for this. I do prefer do use this one instead of accessing the database directly.

I was in need to find the VMUUID assigned to each vRA RequestID for every vm, this can be used to get the values directly from the vRA database.

select P.PropertyValue,V.VirtualMachineName,V.VMUniqueID from VirtualMachine as V join  VirtualMachineProperties as P on V.VirtualMachineID=P.EntityID where V.IsManaged=1 and P.PropertyName='__api.request.id'