Re: [HACKERS] Re: Postgresql bug report - unexpected behavior of suppress_redundant_updates_trigger

On Mon, Jun 19, 2017 at 2:10 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> writes:
>> Tom Lane wrote:
>>> ... If the trigger is succeeding (ie,
>>> detecting a no-op update) often enough that it would be worth that,
>>> you've really got an application-stupidity problem to fix.
>
>> ISTM the whole point of suppress_redundant_updates_trigger is to cope
>> with application stupidity.
>
> I think it's a suitable band-aid for limited amounts of stupidity.
> But it eliminates only a small fraction of the total overhead involved
> in a useless update command. So I remain of the opinion that if that's
> happening a lot, you're better off fixing the problem somewhere upstream.

At first glance I think I'd rather have it do the correct thing all of
the time, even if it takes longer, so that my only trade-off decision
is whether to improve performance by fixing the application.

Ideally if the input tuple wouldn't require compression we wouldn't
bother to decompress the stored tuple.

David J.