On Wed, May 25, 2011 at 10:05 PM, Greg Stark <gsst...@mit.edu> wrote: >> updated_density = old_density + (new_density - old_density) * reliability >> new_reltuples = updated_density * new_relpages > > This amounts to assuming that the pages observed in the vacuum have > the density observed and the pages that weren't seen have the density > that were previously in the reltuples/relpages stats.
In case it's not clear, Tom's expression for updated_density is equivalent by simple algebra to: updated_density = (old_density * (1-reliability)) + (new_density * reliability) -- greg -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
