Re: [GENERAL] Autovacuum Improvements

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%. [...]
> 
> The theory online was that as long as you're reading one page from each disk
> track you're going to pay the same seek overhead as reading the entire track.

Could one take advantage of this observation in designing the DSM?

Instead of a separate bit representing every page, having each bit
represent 20 or so pages might be a more useful unit.  It sounds
like the time spent reading would be similar; while the bitmap
would be significantly smaller.