Best Practice for running vacuums during off hours WAS Re: Autovacuum launcher doesn't notice death of postmaster immediately

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On 6/7/07, Matthew T. O'Connor wrote:

Tom Lane wrote:

"Andrew Hammond" writes:

Hmmm... it seems to me that points new users towards not using
autovacuum, which doesn't seem like the best idea. I think it'd be
better to say that setting the naptime really high is a Bad Idea.

It seems like we should have an upper limit on the GUC variable that's
less than INT_MAX ;-). Would an hour be sane? 10 minutes?

This is independent of the problem at hand, though, which is that we
probably want the launcher to notice postmaster death in less time
than autovacuum_naptime, for reasonable values of same.

Do we need a configurable autovacuum naptime at all? I know I put it in
the original contrib autovacuum because I had no idea what knobs might
be needed. I can't see a good reason to ever have a naptime longer than
the default 60 seconds, but I suppose one might want a smaller naptime
for a very active system?

That's a good question. I can't see any reason for a naptime longer
than 60 seconds either.

I think very large naptime settings are a symptom of another issue:
what's the Right Way to defer vacuums until "off hours"? Is that even
a desirable thing anymore? I don't think it is in the majority of
cases.

I originally thought that this was more of a Best Practices issue (ie,
fix in the docs, not the code), but now I'm wondering if there's much
call for supporting the idea of being more aggressive with vacuums at
different times of the day / week / month. Anyone?
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