Re: [PATCH] Prefetch index pages for B-Tree index scans

> Ok, this is the best I could come up with, without some real test hardware.
> 
> The only improvement I see in single-disk scenarios:
>   * Huge speedup of back-sequential index-only scans
>   * Marginal speedup on forward index-only scans (5% or less)
>   * No discernible difference in heap-including scans (even with heap
> prefetch), but I'm pretty sure a real RAID setup would change this
>   * No change in pgbench (so I guess no regression for small transactions)

If the gain is visible mostly for the backward and not for other access 
patterns I suggest to check the work done in backward-prefecthing in linux. 

http://thread.gmane.org/gmane.linux.kernel.mm/73837 for example

I don't know how others (BSD, windows, ...) handle this case.


Maybe the strategy to use our own prefetch is better, then I would like to use 
it also in places where we used to hack to make linux understand that we will 
benefits from prefetching.

-- 
Cédric Villemain +33 (0)6 20 30 22 52
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