Re: Inserts or Updates

On Tue, Feb 7, 2012 at 4:12 PM, Ofer Israeli <oferi@checkpoint.com> wrote:
> Something specific that you refer to in autovacuum's non-perfection, that is, what types of issues are you aware of?

I refer to its criteria for when to perform vacuum/analyze. Especially
analyze. It usually fails to detect the requirement to analyze a table
- sometimes value distributions change without triggering an
autoanalyze. It's expected, as the autoanalyze works on number of
tuples updates/inserted relative to table size, which is too generic
to catch business-specific conditions.

As everything, it depends on your business. The usage pattern, the
kinds of updates performed, how data varies in time... but in essence,
I've found that forcing a periodic vacuum/analyze of tables beyond
what autovacuum does improves stability. You know a lot more about the
business and access/update patterns than autovacuum, so you can
schedule them where they are needed and autovacuum wouldn't.

> As for the I/O - this is indeed true that it can generate much activity, but the way I see it, if you run performance
testsand the tests succeed in all parameters even with heavy I/O, then you are good to go.  That is, I don't mind the
serverdoing lots of I/O as long as it's not causing lags in processing the messages that it handles. 

If you don't mind the I/O, by all means, crank it up.