Re: Experimental patch for inter-page delay in VACUUM

Zeugswetter Andreas SB SD wrote:

>>Or... It seems to me that we have been observing something on the order
>>of 10x-20x slowdown for vacuuming a table. I think this is WAY
>>overcompensating for the original problems, and would cause it's own
>>problem as mentioned above. Since the granularity of delay seems to be
>>the problem can we do more work between delays? Instead of sleeping
>>after every page (I assume this is what it's doing) perhaps we should
>>sleep every 10 pages,
>>
>>
>
>I also think doing more than one page per sleep is advantageous since
>it would still allow the OS to do it's readahead optimizations.
>I suspect those would fall flat if only one page is fetched per sleep.
>
>

So maybe the setting shouldn't be "n ms wait between vacuum actions" but
"vacuum pages to handle before sleeping 10 ms".

Regards,
Andreas