Jan Wieck wrote:
> Manfred Koizar wrote:
> > On Thu, 21 Aug 2003 21:10:34 +0530, "Shridhar Daithankar"
> > <shridhar_daithankar@persistent.co.in> wrote:
> >>Point I am trying to make is to tune FSM and autovacuum frequency
> >>such that you catch all the dead tuples in RAM
> >
> > You might be able to catch the pages with dead tuples in RAM, but
> > currently there's no way to keep VACUUM from reading in all the clean
> > pages, which can be far more ...
>
> Which leads us to a zero gravity vacuum, that does the lazy vacuum for
> pages currently available in the buffer cache only. And another pg_stat
> column telling the number of tuples vacuumed so that an autovac has a
> chance to avoid IO consuming vacuum runs for relations where 99% of the
> dead tuples have been caught in memory.
What would be really interesting is to look for dead tuples when you
write/discard a buffer page and add them to the FSM --- that is probably
the latest time you still have access to the page and has the highest
probability of being recyclable.
--
Bruce Momjian | http://candle.pha.pa.us
pgman@candle.pha.pa.us | (610) 359-1001
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