| From: | Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org> |
|---|---|
| To: | Simon Riggs <simon(at)2ndquadrant(dot)com> |
| Cc: | Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: Heavy write activity on first vacuum of fresh TOAST data |
| Date: | 2007-12-13 17:26:56 |
| Message-ID: | 20071213172656.GL6262@alvh.no-ip.org |
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| Thread: | |
| Lists: | pgsql-performance |
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)
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