Re: pg_start_backup() takes too long

Simon Riggs <simon@2ndQuadrant.com> writes:
> I'm surprised that checkpoint smoothing moves slowly even when it has so
> little to do.

AFAIK that's operating as designed.  The point being that we shouldn't
create any more I/O load than we absolutely have to.

It's not clear to me that it's a bug for pg_start_backup to take awhile.
If it is a bug then I'd vote for just making it do an immediate
checkpoint --- that might cause big I/O load but it's hardly likely to
be worse than what will happen when you start taking the subsequent
filesystem backup.  The checkpoint code is too complicated already;
I don't want to make it support a third behavior.  And I'd vote against
taking out the current default behavior.

            regards, tom lane