Re: Heavy write activity on first vacuum of fresh TOAST data

[Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>]

Simon Riggs wrote:

> We might be able to have bgwriter set hint bits on dirty blocks, but the
> success of that would depend upon the transit time of blocks through the
> cache, i.e. it might be totally ineffective. So might be just overhead
> for the bgwriter and worse, could divert bgwriter attention away from
> what its supposed to be doing. That's a lot of work to fiddle with the
> knobs to improve things and there's higher things on the list AFAICS.

I don't think that works, because the bgwriter has no access to the
catalogs, therefore it cannot examine the page contents.  To bgwriter,
pages are opaque.

-- 
Alvaro Herrera                  http://www.amazon.com/gp/registry/5ZYLFMCVHXC
"There is evil in the world. There are dark, awful things. Occasionally, we get
a glimpse of them. But there are dark corners; horrors almost impossible to
imagine... even in our worst nightmares." (Van Helsing, Dracula A.D. 1972)