On 28 January 2016 at 17:09, Peter Geoghegan <p...@heroku.com> wrote: > On Thu, Jan 28, 2016 at 9:03 AM, Thom Brown <t...@linux.com> wrote: >> I'm surprised that efficiencies can't be realised beyond this point. Your >> results show a sweet spot at around 1000 / 10000000, with it getting >> slightly worse beyond that. I kind of expected a lot of efficiency where >> all the values are the same, but perhaps that's due to my lack of >> understanding regarding the way they're being stored. > > I think that you'd need an I/O bound workload to see significant > benefits. That seems unsurprising. I believe that random I/O from > index writes is a big problem for us.
I was thinking more from the point of view of the index size. An index containing 10 million duplicate values is around 40% of the size of an index with 10 million unique values. Thom -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
