Re: More detail on settings for pgavd?

Shridhar,

> I would say -V 0.2-0.4 could be great as well. Fact to emphasize is that
> thresholds less than 1 should be used.

Yes, but not thresholds, scale factors of less than 1.0.  Thresholds should
still be in the range of 100 to 1000.

> I will submit a patch that would account deletes in analyze threshold.
> Since you want to delay the analyze, I would calculate analyze count as
>
> n=updates + inserts *-* deletes

I'm not clear on how this is a benefit.  Deletes affect the statistics, too.

> What does statistics gather BTW? Just number of rows or something else as
> well? I think I would put that on Hackers separately.

Number of tuples, degree of uniqueness, some sample values, and high/low
values.   Just query your pg_statistics view for an example.

> I am still wary of inverting vacuum analyze frequency. You think it is
> better to set inverted default rather than documenting it?

See my post to Matthew.

--
Josh Berkus
Aglio Database Solutions
San Francisco