Joe Conway wrote:
> In my experience it is almost always best to run autovacuum very often
> and very aggressively. That generally means tuning scaling factor and
> thresholds as well, such that there are never more than say 50-100k dead
> rows. Then running vacuum with no delays or limits runs quite fast is is
> generally not noticeable/impactful.
>
> However that strategy does not work well for vacuums which run long,
> such as an anti-wraparound vacuum. So in my opinion we need to think
> about this as at least two distinct cases requiring different solutions.
With the freeze map there is no need for anti-wraparound vacuums to be
terribly costly, since they don't need to scan the whole table each
time. That patch probably changes things a lot in this area.
--
Álvaro Herrera http://www.2ndQuadrant.com/
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