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

--- Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)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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