Marcos Pegoraro <marcos@f10.com.br> writes:
> But it takes resources for other operations, right ?
> I think this is not unusual. If an user double click on a grid, just sees a
> record and clicks ok to save, probably that application calls an update
> instead of seeing if some field were changed before that.
[ shrug... ] As David said, if you think that it's important to have
such a check in a particular application, use a trigger to check it.
There's one built-in, you don't even need an extension:
https://www.postgresql.org/docs/current/functions-trigger.html
We're not going to make that happen by default though, because it'd
be a net drag on better-written applications.
regards, tom lane