Re: [HACKERS] Autovacuum Improvements

On Mon, Jan 22, 2007 at 05:51:53PM +0000, Gregory Stark wrote:
> Actually no. A while back I did experiments to see how fast reading a file
> sequentially was compared to reading the same file sequentially but skipping
> x% of the blocks randomly. The results were surprising (to me) and depressing.
> The breakeven point was about 7%.

I asusume this means you were reading 7% of the blocks, not skipping 7%
of the blocks when you broke even?

I presume by break-even you mean it took just as long, time-wise. But
did it have the same effect on system load? If reading only 7% of the
blocks allows the drive to complete other requests more quickly then
it's beneficial, even if the vacuum takes longer.

This may be a silly thought, I'm not sure how drives handle multiple
requests...

Have a nice day,
--
Martijn van Oosterhout   <kleptog@svana.org>   http://svana.org/kleptog/
> From each according to his ability. To each according to his ability to litigate.