Re: Some thoughts about i/o priorities and throttling vacuum

Bruce Momjian <pgman@candle.pha.pa.us> writes:
> Of course, this makes VACUUM run longer, and if you are waiting for it
> to finish, it would be worse, like if you are running it at night or
> something.
> I think the delay has to take into account the number of active
> transactions or something.

I was just thinking of a GUC parameter: wait N milliseconds between
pages, where N defaults to zero probably.  A user who wants to run his
vacuum as a background process could set N larger than zero.  I don't
believe we are anywhere near being able to automatically adjust the
delay based on load, and even if we could, this would ignore the point
you make above --- the user's intent has to matter as much as anything
else.
        regards, tom lane