Re: Postgresql 8.0 beta 1 - strange cpu usage statistics and slow vacuuming

--- Tom Lane <tgl@sss.pgh.pa.us> wrote:
>
> > My other concern is the length of time that vacuum
> > runs when cost based vacuuming is disabled.
>
> Are you sure you had cost-based vac disabled?  I
> tried to reproduce
> your experiment here.  I saw some degradation in
> vacuuming speed
> but not nearly as large as you're reporting (85 vs
> 73 seconds),
> and as far as I could tell it was still maxing out
> my disk.
> But the behavior you're describing is exactly what
> I'd expect if
> cost-based vac was on.
>

I'm pretty certain.  Here are my settings:

vacuum_cost_delay = 0        # 0-1000 milliseconds
vacuum_cost_page_hit = 1    # 0-10000 credits
vacuum_cost_page_miss = 10    # 0-10000 credits
vacuum_cost_page_dirty = 20    # 0-10000 credits
vacuum_cost_limit = 200        # 0-10000 credits

From looking at vacuum.c I gathered vacuum_cost_delay
must be >0 to enable the feature - correct?

Regards,

Shelby Cain





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