Re: Re: [WIP] Performance Improvement by reducing WAL for Update Operation

Noah Misch <noah@leadboat.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