On 2017-03-06 18:59:02 -0500, Robert Haas wrote: > On Mon, Mar 6, 2017 at 5:19 PM, Andres Freund <and...@anarazel.de> wrote: > > The whole performance issue trigger this thread only exists when the > > hashtable sizes are mis-estimated, right? Turns out that after applying > > the just-committed changes, that "fixing" the bad-mixing and/or doing > > iteration that's not entirely in hash-order, slighty degrades > > performance. The difference is that without either of those additional > > changes, we resize to the "right" size very early, when the hashtable is > > barely filled (i.e. only few entries need to be moved), because the > > imbalance is observed at tsart. With the changes however the resizing > > happens when the table is pretty full (i.e. a lot of entries need to be > > moved). So the early imbalance ends up actually not hurting > > performance... > > Hmm. I don't know what to do about that.
Oh, I don't think we need to do much about it either way - I think it's more an interesting curiosity than anything. Seems to reduce the urgency for better iteration a bit, that's it. - Andres -- Sent via pgsql-hackers mailing list (firstname.lastname@example.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers