* Alvaro Herrera (alvhe...@2ndquadrant.com) wrote: > Alvaro Herrera wrote: > > Basically, if you are on 9.3.5 or earlier any per-table options for > > autovacuum cost delay will misbehave (meaning: any such table will be > > processed with settings flattened according to balancing of the standard > > options, _not_ the configured ones). If you are on 9.3.6 or newer they > > will behave as described in the docs. > > Another thing to note is that if you have configured a table to have > cost_limit *less* than the default (say 150 instead of the default 200), > the balance system will again break that and process the table at 200 > instead; in other words, the balancing system has completely broken the > ability to tweak the cost system for individual tables in autovacuum.
That's certainly pretty ugly.
> With the v5 patch, the example tables above will be vacuumed at exactly
> 5000 and 150 instead. The more complex patch I produced earlier would
> have them vacuumed at something like 4900 and 100 instead, so you
> wouldn't exceed the total of 5000. I think there is some value to that
> idea, but it seems the complexity of managing this is too high.
Agreed.
> I am rather surprised that nobody has reported this problem before. I
> am now of the mind that this is clearly a bug that should be fixed all
> the way back.
I'm coming around to that also, however, should we worry about users who
set per-table settings and then simply forgot about them? I suppose
that won't matter too much unless the table is really active, and if it
is, they've probably already set it to zero.
Thanks,
Stephen
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