Re: visibility map and reltuples

Greg Stark wrote:
> I wonder if we should switch to keeping reltuplesperpage instead. Then a 
> partial vacuum could update it by taking the average number of tuples 
> per page forbthe pages it saw. Perhaps adjusting it to the weights 
> average between the old value and the new value based on how many pages 
> were seen.

The pages scanned by a partial vacuum isn't a random sample of pages in 
the table. That would bias the reltuplesperpage value towards those 
pages that are updated more.

--   Heikki Linnakangas  EnterpriseDB   http://www.enterprisedb.com