Michael Paesold wrote:
> Simon Riggs wrote:
>> On Thu, 2007-10-25 at 13:41 -0300, Alvaro Herrera wrote:
> ...
>>> FWIW I disagree with cancelling just any autovac work automatically; in
>>> my patch I'm only cancelling if it's analyze, on the grounds that if
>>> you have really bad luck you can potentially lose a lot of work that
>>> vacuum did.  We can relax this restriction when we have cancellable
>>> vacuum.
>> That was requested by others, not myself, but I did agree with the
>> conclusions. The other bad luck might be that you don't complete some
>> critical piece of work in the available time window because an automated
>> job kicked in.
> Yeah, I thought we had agreed that we must cancel all auto vacuum/analyzes, 
> on the ground that foreground operations are usually more important than 
> maintenance tasks.

What this means is that autovacuum will be starved a lot of the time,
and in the end you will only vacuum the tables when you run out of time
for Xid wraparound.

> Remember the complaint we already had on hackers just after beta1:
> auto *vacuum* blocked a schema change, and of course the user
> complained.

Actually I can't remember it, but I think we should decree that this is
a known shortcoming; that we will fix it when we have cancellable
vacuum; and that the user is free to cancel the vacuuming on his own if
he so decides.

Alvaro Herrera                         http://www.flickr.com/photos/alvherre/
"The ability to monopolize a planet is insignificant
next to the power of the source"

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