Re: perfromance impact of vacuum

On Tue, Jul 15, 2003 at 11:04:53AM -0700, Jay O'Connor wrote:
> Actually what I meant is how long the vacuum runs. We're going to have a
> big database (few TB projected, but I don't know where those numbers come
> from) and I'm trying to ausage concerns that vacuuming will impact
> performance significantly.

It depends very heavily on your expired-tuple percentage. But it is
still not free to vacuum a large table. And vacuum full always scans
the whole table.

Remember that vacuum operates on tables, which automatically means
that it does nasty things to your cache.

The stand-alone analyse can be helpful here. It only does
samples of the tables under analysis, so you don't face the same I/O
load. If all you're doing is adding to a table, it may be worth
investigating. Keep in mind, though, you still need to vacuum every
2 billion transactions.

A

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