For a documentation patch should this not be back ported to all
relevant versions?
On 8/21/10, Bruce Momjian <bruce@momjian.us> wrote:
> Josh Berkus wrote:
>>
>> > 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.
>
> We often mention that we do vacuum freeze for anti-wraparound vacuum,
> but not for pg_clog file removal, which is the primary trigger for
> autovacuum vacuum freezing. I have added the attached documentation
> patch for autovacuum_freeze_max_age; back-patched to 9.0.
>
> --
> Bruce Momjian <bruce@momjian.us> http://momjian.us
> EnterpriseDB http://enterprisedb.com
>
> + It's impossible for everything to be true. +
>
--
Rob Wultsch
wultsch@gmail.com