Benjamin Arai <me(at)benjaminarai(dot)com> writes:
> Why is a trigger faster than doing a ALTER after table is created? I
> thought a trigger would be slower because it would be invoked every
> iteration (a new row is inserted) during the COPY process.
Yeah, you'd have the trigger overhead, but the above argument ignores
the costs of the full-table UPDATE --- not to mention the VACUUM
you'll need after the UPDATE to clean up the dead rows.
regards, tom lane