On Sun, Sep 10, 2017 at 9:39 PM, Peter Geoghegan <p...@bowt.ie> wrote: > To be clear, you'll still need to set replacement_sort_tuples high > when testing RS, to make sure that we really use it for at least the > first run when we're expected to. (There is no easy way to have > testing mechanically verify that we really do only have one run in the > end with RS, but I assume that such paranoia is unneeded.)
I seem to recall that raising replacement_sort_tuples makes replacement selection look worse in some cases -- the optimization is more likely to apply, sure, but the heap is also bigger, which hurts. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
