Noah Misch <noah(at)leadboat(dot)com> writes:
> You cannot assume executor-unmodified columns are also unmodified from
> heap_update()'s perspective. Expansion in one column may instigate TOAST
> compression of a logically-unmodified column, and that counts as a change for
> xlog delta purposes.
Um ... what about BEFORE triggers?
Frankly, I think that expecting the executor to tell you which columns
have been modified is a non-starter. We have a solution for HOT and
it's silly to do the same thing differently just a few lines away.
regards, tom lane