Re: BUG #15840: Vacuum does not work after database stopped forwraparound protection. Database seems unrepearable.

On 2019-Jun-07, Thierry Husson wrote:

> Yes autovacuum is enabled. Aggressiveness was effectively a recent problem I
> had and putting its max_worker to 8 wasn't a solution, there were all busy
> 24/7 and I had to do a daily script to help it. The solution was to push
> vacuum_cost_limit to 2000, since then it works like a charm.

Note the I/O cost balancing thing, which seems to bite many people: if
you raise max_workers without changing cost_delay or cost_limit, it
doesn't have much of an effect, because each worker goes slower to
accomodate.  Raising the cost limit (or lowering the cost delay) does
have a useful impact.  In pg12 we changed the default cost_delay to 2ms
(from 20ms).

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
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