Re: update behavior

Scott Ribe <scott_ribe(at)elevated-dev(dot)com> writes:
> I believe that if I UPDATE a row with the same values that it already has, this still dirties pages, writes the row, generates a WAL entry. There is no shortcut in the processing that's "hey, there's not really a change here, we'll just leave storage alone".

> Is this correct?

It is. We do offer a trigger you can add to suppress zero-change
updates [1], but that's not the default behavior. We judged that
checking for that would add more cycles than it removes, for most
applications most of the time.

regards, tom lane

[1] https://www.postgresql.org/docs/current/functions-trigger.html