it is done using now()....
But what I don't understand is how the transaction that started first
could 'see' the record that hadn't been changed yet by the initial
update to 'COMPLETE'?
I thought:
"Each transaction sees a snapshot (database version) as of its
starttime, no matter what other transactions are doing while it runs"
> How is the "when" column determined? You did not show it in your SQL
> commands.
>
> If it's being driven off now() or CURRENT_TIMESTAMP, then the above
> isn't all that surprising, because the value is the time of transaction
> start not the time at which the update was made.
>
>