Re: query slows down with more accurate stats

Manfred Koizar <mkoi-pg(at)aon(dot)at> writes:
> My biggest concern at the moment is that the new sampling method
> violates the contract of returning each possible sample with he same
> probability: getting several tuples from the same page is more likely
> than with the old method.

Hm, are you sure? I recall objecting to your original proposal because
I thought that would happen, but after further thought it seemed not.

Also, I'm not at all sure that the old method satisfies that constraint
completely in the presence of nonuniform numbers of tuples per page,
so we'd not necessarily be going backwards anyhow ...

regards, tom lane