On Thu, Mar 1, 2012 at 4:35 PM, Alessandro Gagliardi
<alessandro@path.com> wrote:
> Interesting solution. If I'm not mistaken, this does solve the problem of
> having two entries for the same user at the exact same time (which violates
> my pk constraint) but it does so by leaving both of them out (since there is
> no au1.hr_timestamp > au2.hr_timestamp in that case). Is that right?
Yes, but it would have to be same *exact* time (not same hour).
You can use more fields to desambiguate too, ie:
au1.hr_timestamp > au2.hr_timestamp or (au1.hr_timestamp ==
au2.hr_timestamp and au1.some_other_field > au2.some_other_field)
If you have a sequential id to use in desambiguation, it would be best.