> On further reflection, though: since we put in the BufferAccessStrategy
> code, which was in 8.3, the background writer isn't *supposed* to be
> very much involved in writing pages that are dirtied by VACUUM. VACUUM
> runs in a small ring of buffers and is supposed to have to clean its own
> dirt most of the time. So it's wrong to blame this on the bgwriter not
> holding up its end. Rather, what you need to be thinking about is how
> come vacuum seems to be making lots of pages dirty on only one of these
> machines.
This is an anti-wraparound vacuum, so it could have something to do with
the hint bits. Maybe it's setting the freeze bit on every page, and
writing them one page at a time? Still don't understand the call to
pollsys, even so, though.
-- -- Josh Berkus PostgreSQL Experts Inc.
http://www.pgexperts.com
