Re: the big picture for index-only scans

On Jun19, 2011, at 23:16 , Robert Haas wrote:
> On Sun, Jun 19, 2011 at 5:10 PM, Florian Pflug <fgp@phlo.org> wrote:
>> On Jun19, 2011, at 20:40 , Robert Haas wrote:
>>> 2. Since VACUUM and ANALYZE often run together, we will be estimating
>>> the percentage of rows on all-visible pages just at the time when that
>>> percentage is highest.  This is not exactly wonderful, either...
>> 
>> Hm, doesn't autovacuum run ANALYZE quite a bit more frequently than
>> VACUUM by default?
> 
> The autoanalyze threshold is, by default, 10%; and the autovacuum
> threshold, 20%.

Hm, so you could ignore (or rather dampen) the results of 
VACUUM+ANALYZE and rely on the ANALYZE-only runs to keep
the estimate correct. Still doesn't sound that bad...

best regards,
Florian Pflug